New Valencia head coach Gary Neville watched from the stand as Santi Mina's equaliser ensured La Liga leaders Barcelona were held to a draw.
Luis Suarez's 44th goal in 64 matches for Barca looked to have earned them a seventh straight league win.
The home side, led by interim head coach Voro and Neville's brother Phil, were second best for long spells.
But the visitors paid for missing a host of chances as forward Mina, who turns 20 on Monday, lashed in late on.
It was the teenager's first goal since joining Valencia from Celta Vigo in the summer, and came after Paco Alcacer had chested down a long ball to set him up.
Neville, who takes charge officially on Sunday, arrives at the Mestalla to take over a team languishing in the middle of La Liga after qualifying for the Champions League in May.
He will have been encouraged by a Valencia performance far better than was put forward in the 1-0 defeat at Sevilla last Sunday that preceded Nuno Espirito Santo's resignation.
This was a point earned against the odds. Valencia were missing 10 senior players for the visit of the Spanish champions, and it showed at times.
Ruben Vezo, normally a centre-back, was pressed into service as a stand-in right-back, and had a torrid night against Neymar, not helped at times by a lack of defensive support from Mina.
Another concern for Neville would be Valencia's inability to keep the ball when they had it. Too many passes went astray, inviting pressure on an overworked back line.
However, they hung in when they could have gone under, and got reward in the closing minutes.
Despite the adrenaline rush that would have come with Mina's late equaliser, Neville will be honest enough to acknowledge that Barcelona should have won.
The league leaders' big weakness was their profligacy in front of goal. Their formidable front three of Neymar, Suarez and Lionel Messi all missed chances they would have expected to score in the first half.
Neymar blazed a shot over in the first half after Vezo had lost his man, then curled a terrific effort just wide in the second, while Suarez gave Valencia a let off with a wayward chip when clear before the interval, and Messi's normally clinical finishing was missing.
Despite their dominance, Barca could not pull away. They received a warning when Rodrigo De Paul hit a tame shot at keeper Claudio Bravo with 12 minutes left, but did not heed it - and Mina punished them.
On a day that both Madrid clubs posted victories to maintain the pressure in the title race, Luis Enrique's side missed a great chance to post a statement of intent - and saw their title lead cut to a point.
Luis Suarez has made a career out of playing on the edge - proving as prone to crossing the line as hitting the heights.
The Mestalla saw the worst and the best of Suarez in the space of a few minutes in the second half.
First, the Uruguay striker was picked up by television cameras stamping on the foot of Aymen Abdennour. The Valencia centre-back made clear his anger as he fell to the turf, while Suarez, pleading his innocence, escaped without censure.
Moments later, though, Suarez showed just why he has become one of the most coveted attacking talents in world football, finishing ruthlessly to put his team in front.
There was a suggestion that Suarez might have been offside as he raced on to Messi's pass, although Vezo may just have been playing him onside.
The new head coach takes over the reigns from the popular Voro for Wednesday's crucial Champions League home match against Lyon.
A win will ensure Neville's new team a place in the last 16 - as long as Gent do not beat Zenit St Petersburg in the night's other Group H fixture.
After that comes a La Liga trip to seventh-placed Eibar, which must be faced without captain Daniel Parejo, suspended after picking up a fifth booking of the season for chopping down Suarez in the second half.
Full Time Match ends, Valencia CF 1, Barcelona 1.
90:00 +3:03 Full timeFull Time Second Half ends, Valencia CF 1, Barcelona 1.
90:00 +2:13Foul by Gerard Piqué (Barcelona).
90:00 +2:13José Gayá (Valencia CF) wins a free kick in the defensive half.
90:00 +1:45Corner, Barcelona. Conceded by Aderlan Santos.
90:00 +1:05Foul by Andrés Iniesta (Barcelona).
90:00 +1:05Daniel Parejo (Valencia CF) wins a free kick in the defensive half.
90:00 +0:31Attempt saved. Lionel Messi (Barcelona) left footed shot from outside the box is saved in the centre of the goal. Assisted by Luis Suárez.
89:29Foul by Sergio Busquets (Barcelona).
89:29Danilo (Valencia CF) wins a free kick in the defensive half.
88:19Attempt saved. Danilo (Valencia CF) left footed shot from outside the box is saved in the top centre of the goal. Assisted by Zakaria Bakkali.
87:34Corner, Barcelona. Conceded by Jaume.
87:32Attempt saved. Lionel Messi (Barcelona) left footed shot from outside the box is saved in the top right corner.
87:09 SubstitutionSubstitution Substitution, Valencia CF. Tropi replaces Santi Mina.
86:37 BookingBooking José Gayá (Valencia CF) is shown the yellow card for a bad foul.
86:27Lionel Messi (Barcelona) wins a free kick on the right wing.
86:27Foul by José Gayá (Valencia CF).
85:03 Goal scoredGoal! Goal! Valencia CF 1, Barcelona 1. Santi Mina (Valencia CF) right footed shot from the centre of the box to the bottom right corner. Assisted by Paco Alcácer following a fast break.
83:49Corner, Barcelona. Conceded by Aderlan Santos.
82:15 SubstitutionSubstitution Substitution, Valencia CF. Pablo Piatti replaces Rodrigo de Paul.
Attempt missed. Zakaria Bakkali (Valencia CF) right footed shot from outside the box is high and wide to the right. Assisted by Rodrigo de Paul following a fast break.
78:13Attempt saved. Rodrigo de Paul (Valencia CF) right footed shot from outside the box is saved in the bottom left corner.
77:32Offside, Barcelona. Neymar tries a through ball, but Sergio Busquets is caught offside.
76:34 BookingBooking Danilo (Valencia CF) is shown the yellow card for a bad foul.
76:26Lionel Messi (Barcelona) wins a free kick on the right wing.
76:26Foul by Danilo (Valencia CF).
73:26Attempt missed. Neymar (Barcelona) right footed shot from the centre of the box is close, but misses to the right. Assisted by Jordi Alba.
72:07 SubstitutionSubstitution Substitution, Valencia CF. Zakaria Bakkali replaces Enzo Pérez because of an injury.
71:48Delay over. They are ready to continue.
71:40Delay in match Enzo Pérez (Valencia CF) because of an injury.
69:58 BookingBooking Daniel Parejo (Valencia CF) is shown the yellow card for a bad foul.
69:54Luis Suárez (Barcelona) wins a free kick in the defensive half.
69:54Foul by Daniel Parejo (Valencia CF).
68:23Foul by Luis Suárez (Barcelona).
68:23Aymen Abdennour (Valencia CF) wins a free kick in the defensive half.
65:40Foul by Neymar (Barcelona).
65:40Daniel Parejo (Valencia CF) wins a free kick on the right wing.
65:09Foul by Neymar (Barcelona).
65:09Rúben Vezo (Valencia CF) wins a free kick in the defensive half.
62:01Foul by Lionel Messi (Barcelona).
62:01José Gayá (Valencia CF) wins a free kick in the defensive half.
61:10Corner, Barcelona. Conceded by Aderlan Santos.
60:31Attempt missed. Danilo (Valencia CF) right footed shot from outside the box misses to the left.
60:25Attempt blocked. Daniel Parejo (Valencia CF) right footed shot from outside the box is blocked.
59:49Attempt saved. Luis Suárez (Barcelona) right footed shot from the centre of the box is saved in the centre of the goal. Assisted by Ivan Rakitic with a through ball.
58:02 Goal scoredGoal! Goal! Valencia CF 0, Barcelona 1. Luis Suárez (Barcelona) right footed shot from the right side of the six yard box to the bottom right corner. Assisted by Lionel Messi.
57:24Attempt blocked. Luis Suárez (Barcelona) left footed shot from outside the box is blocked.
57:03Dani Alves (Barcelona) wins a free kick on the right wing.
57:03Foul by Rodrigo de Paul (Valencia CF).
53:50Delay over. They are ready to continue.
53:00Delay in match Jaume (Valencia CF) because of an injury.
52:24Foul by Luis Suárez (Barcelona).
52:24Jaume (Valencia CF) wins a free kick in the defensive half.
51:38Sergio Busquets (Barcelona) wins a free kick in the defensive half.
51:38Foul by Rodrigo de Paul (Valencia CF).
47:03Offside, Barcelona. Neymar tries a through ball, but Luis Suárez is caught offside.
46:13Attempt blocked. Lionel Messi (Barcelona) left footed shot from outside the box is blocked.
45:00Second Half begins Valencia CF 0, Barcelona 0.
45:00 +1:05 Half timeHalf Time First Half ends, Valencia CF 0, Barcelona 0.
45:00 +0:01Luis Suárez (Barcelona) wins a free kick in the attacking half.
45:00 +0:01Foul by Aymen Abdennour (Valencia CF).
43:54Andrés Iniesta (Barcelona) wins a free kick in the attacking half.
43:54Foul by Danilo (Valencia CF).
42:25Dani Alves (Barcelona) wins a free kick in the defensive half.
42:25Dangerous play by Rodrigo de Paul (Valencia CF).
40:02Foul by Lionel Messi (Barcelona).
40:02Rodrigo de Paul (Valencia CF) wins a free kick in the defensive half.
39:00Corner, Barcelona. Conceded by Aderlan Santos.
35:57Attempt blocked. Ivan Rakitic (Barcelona) left footed shot from the right side of the box is blocked.
35:55Attempt blocked. Ivan Rakitic (Barcelona) right footed shot from the right side of the box is blocked.
35:12Jordi Alba (Barcelona) wins a free kick on the left wing.
35:12Foul by Santi Mina (Valencia CF).
33:50Foul by Luis Suárez (Barcelona).
33:50Daniel Parejo (Valencia CF) wins a free kick in the defensive half.
33:07Attempt missed. Luis Suárez (Barcelona) right footed shot from long range on the right is too high. Assisted by Neymar.
32:23Foul by Andrés Iniesta (Barcelona).
32:23Daniel Parejo (Valencia CF) wins a free kick in the defensive half.
27:03Foul by Andrés Iniesta (Barcelona).
27:03Santi Mina (Valencia CF) wins a free kick in the defensive half.
25:17Attempt saved. Lionel Messi (Barcelona) right footed shot from the centre of the box is saved in the centre of the goal. Assisted by Neymar.
24:41Corner, Barcelona. Conceded by Santi Mina.
23:24Attempt missed. Sergio Busquets (Barcelona) right footed shot from outside the box misses to the left.
23:22Attempt blocked. Lionel Messi (Barcelona) left footed shot from outside the box is blocked. Assisted by Dani Alves.
21:09Foul by Ivan Rakitic (Barcelona).
21:09Enzo Pérez (Valencia CF) wins a free kick in the defensive half.
19:43Sergio Busquets (Barcelona) wins a free kick in the attacking half.
19:43Foul by Paco Alcácer (Valencia CF).
18:45Foul by Dani Alves (Barcelona).
18:45José Gayá (Valencia CF) wins a free kick on the left wing.
16:16Attempt blocked. Enzo Pérez (Valencia CF) right footed shot from outside the box is blocked. Assisted by Rodrigo de Paul.
15:45Delay over. They are ready to continue.
15:23 BookingBooking Javier Mascherano (Barcelona) is shown the yellow card for a bad foul.
14:50Delay in match Javier Mascherano (Barcelona) because of an injury.
14:35Foul by Javier Mascherano (Barcelona).
14:35Santi Mina (Valencia CF) wins a free kick on the right wing.
13:59Neymar (Barcelona) wins a free kick on the left wing.
13:59Foul by Santi Mina (Valencia CF).
13:12Neymar (Barcelona) wins a free kick in the defensive half.
13:12Foul by Danilo (Valencia CF).
12:19Offside, Barcelona. Ivan Rakitic tries a through ball, but Dani Alves is caught offside.
9:44Attempt blocked. Lionel Messi (Barcelona) left footed shot from the centre of the box is blocked. Assisted by Neymar.
9:12Attempt missed. Rodrigo de Paul (Valencia CF) right footed shot from outside the box misses to the right. Assisted by Aymen Abdennour.
7:14Neymar (Barcelona) wins a free kick in the defensive half.
7:14Foul by Rúben Vezo (Valencia CF).
5:28Attempt missed. Neymar (Barcelona) right footed shot from the left side of the box is too high.
4:31Attempt missed. Lionel Messi (Barcelona) left footed shot from the centre of the box is just a bit too high. Assisted by Neymar with a cross.
2:48Attempt missed. Santi Mina (Valencia CF) right footed shot from a difficult angle on the right is close, but misses to the right.
2:42Attempt blocked. Rodrigo de Paul (Valencia CF) right footed shot from the left side of the box is blocked. Assisted by Enzo Pérez.
0:00First Half begins.
0:00Lineups are announced and players are warming up.
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