Son Heung-min scored a stunning goal and set up another as Tottenham booked their place in the FA Cup fourth round at the expense of Leicester.
With both sides flying high in the Premier League, it promised to be a closely fought replay after the sides drew the first match.
But Spurs were barely troubled and took the lead in the 39th minute when Son's 18-yard strike beat Kasper Schmeichel.
Nacer Chadli made it 2-0 when he converted Son's precise through ball.
The north London side travel to League One strugglers Colchester United in the fourth round.
It was probably the best 83 minutes of Son's Tottenham career so far.
The £22m summer signing from Bayer Leverkusen was the one bright spark in attack on a night when both sides lacked bite up front.
With Tottenham pairing Harry Kane and Dele Alli and the Foxes' Jamie Vardy and Riyad Mahrez starting on the bench, it was up to the 'cup players' to prove they were also worthy of a place in their Premier League starting XIs.
For Tottenham, who made eight changes, Son's claim was the strongest. He did what his team-mates struggled to do for almost 40 minutes - penetrate the Leicester backline when he shifted past defender Ben Chilwell before scoring with a ferocious dipping strike.
And his assist for the second was also a thing of beauty. After collecting substitute Kane's pass from the left, Son nutmegged Yohan Benalouane with his ball for Chadli, who fired beyond Schmeichel.
'Tinkerman' Claudio Ranieri repeated much of what he had done before the first match by making nine changes from the previous league match.
As in the first game, his side were content to let Tottenham dominate possession seemingly in the hope of catching them on the break.
However, the plan failed. The Spurs midfield quelled the threat of wingers Demarai Gray and Nathan Dyer, and in doing so cut off the supply line for lone striker Leonardo Ulloa.
Shinji Okazaki and Marc Albrighton were brought on after the break, as in the match at White Hart Lane, and improved matters. Albrighton had the Foxes best chance of the match when he forced a good low save from the otherwise redundant Michel Vorm.
In defence, Chilwell should perhaps have closed down Son for the opener, but he was Leicester's best player. The youngster was exceptional as an attacking full-back - the highlight a mazy first-half run that won his side a free-kick.
But it is now only one win in seven games for the Foxes in all competitions - is this more than a blip?
Tottenham manager Mauricio Pochettino: "We have also the Premier League and Europa League and I think it is very important to keep the squad fit and working hard, and the FA Cup is very important for this. We are having a fantastic season, we are at a fantastic level.
"It is difficult to be fair to players but there is fantastic spirit in the changing room and in the training ground.
"I don't like to speak about change. For me, when you have 24 or 25 players they all work very hard and some players deserve to play and can't - you can only pick 11 and seven on the bench."
Leicester boss Claudio Ranieri: "Tonight, Tottenham deserved to win. Our priority is the Premier League.
"The FA Cup, I wanted to see all my players and they played at their maximum. I'm very, very pleased with their performance."
Leicester are back in league action at home to Stoke on Saturday, and Tottenham are at Crystal Palace.
Full Time Match ends, Leicester City 0, Tottenham Hotspur 2.
90:00 +3:03 Full timeFull Time Second Half ends, Leicester City 0, Tottenham Hotspur 2.
90:00 +2:30Corner, Leicester City. Conceded by Michel Vorm.
90:00 +2:24Attempt saved. Leonardo Ulloa (Leicester City) header from the centre of the box is saved in the top centre of the goal. Assisted by Marc Albrighton with a cross.
90:00 +2:04Foul by Dele Alli (Tottenham Hotspur).
90:00 +2:04Marc Albrighton (Leicester City) wins a free kick on the right wing.
90:00 +0:24Harry Kane (Tottenham Hotspur) wins a free kick in the defensive half.
90:00 +0:24Foul by Marc Albrighton (Leicester City).
89:25 BookingBooking Marc Albrighton (Leicester City) is shown the yellow card for a bad foul.
89:23Dele Alli (Tottenham Hotspur) wins a free kick on the left wing.
89:23Foul by Marc Albrighton (Leicester City).
89:12Attempt saved. Marc Albrighton (Leicester City) right footed shot from the centre of the box is saved in the bottom right corner. Assisted by Ben Chilwell with a cross.
88:13Dele Alli (Tottenham Hotspur) wins a free kick on the left wing.
88:13Foul by Marcin Wasilewski (Leicester City).
86:37Attempt blocked. Jamie Vardy (Leicester City) left footed shot from outside the box is blocked. Assisted by Leonardo Ulloa.
84:46Attempt missed. Demarai Gray (Leicester City) right footed shot from outside the box is just a bit too high. Assisted by Shinji Okazaki.
83:23 SubstitutionSubstitution Substitution, Tottenham Hotspur. Dele Alli replaces Son Heung-Min.
78:29Offside, Leicester City. Demarai Gray tries a through ball, but Shinji Okazaki is caught offside.
75:58Corner, Tottenham Hotspur. Conceded by Yohan Benalouane.
75:56Attempt blocked. Son Heung-Min (Tottenham Hotspur) right footed shot from outside the box is blocked.
Attempt blocked. Tom Carroll (Tottenham Hotspur) left footed shot from outside the box is blocked. Assisted by Son Heung-Min.
74:31Harry Kane (Tottenham Hotspur) wins a free kick on the left wing.
74:31Foul by Marcin Wasilewski (Leicester City).
73:30 SubstitutionSubstitution Substitution, Leicester City. Jamie Vardy replaces Nathan Dyer.
72:55 SubstitutionSubstitution Substitution, Tottenham Hotspur. Josh Onomah replaces Nacer Chadli.
71:57Attempt saved. Harry Kane (Tottenham Hotspur) left footed shot from outside the box is saved in the bottom right corner. Assisted by Tom Carroll.
70:56Corner, Leicester City. Conceded by Nacer Chadli.
70:52Attempt blocked. Andy King (Leicester City) right footed shot from outside the box is blocked.
70:06Foul by Eric Dier (Tottenham Hotspur).
70:06Andy King (Leicester City) wins a free kick in the attacking half.
65:22 Goal scoredGoal! Goal! Leicester City 0, Tottenham Hotspur 2. Nacer Chadli (Tottenham Hotspur) left footed shot from the left side of the box to the centre of the goal. Assisted by Son Heung-Min with a through ball.
62:59 SubstitutionSubstitution Substitution, Leicester City. Marc Albrighton replaces Danny Simpson.
62:24Hand ball by Son Heung-Min (Tottenham Hotspur).
61:33Attempt saved. Harry Kane (Tottenham Hotspur) right footed shot from the right side of the box is saved in the bottom right corner. Assisted by Son Heung-Min.
59:46 SubstitutionSubstitution Substitution, Tottenham Hotspur. Harry Kane replaces Erik Lamela.
58:02Foul by Erik Lamela (Tottenham Hotspur).
58:02Gökhan Inler (Leicester City) wins a free kick in the defensive half.
57:01Foul by Son Heung-Min (Tottenham Hotspur).
57:01Andy King (Leicester City) wins a free kick in the attacking half.
55:58Foul by Kevin Wimmer (Tottenham Hotspur).
55:58Leonardo Ulloa (Leicester City) wins a free kick in the attacking half.
54:42Hand ball by Nathan Dyer (Leicester City).
52:37Attempt missed. Nathan Dyer (Leicester City) right footed shot from a difficult angle on the right is high and wide to the right.
52:36Attempt saved. Demarai Gray (Leicester City) right footed shot from the left side of the box is saved in the bottom right corner. Assisted by Andy King.
50:21Corner, Tottenham Hotspur. Conceded by Yohan Benalouane.
49:53Corner, Tottenham Hotspur. Conceded by Yohan Benalouane.
47:54Foul by Nacer Chadli (Tottenham Hotspur).
47:54Ben Chilwell (Leicester City) wins a free kick in the defensive half.
45:53Corner, Tottenham Hotspur. Conceded by Ben Chilwell.
45:00Second Half begins Leicester City 0, Tottenham Hotspur 1.
45:00 SubstitutionSubstitution Substitution, Leicester City. Shinji Okazaki replaces Daniel Drinkwater.
45:00 +1:11 Half timeHalf Time First Half ends, Leicester City 0, Tottenham Hotspur 1.
45:00 +1:03Attempt missed. Kevin Wimmer (Tottenham Hotspur) left footed shot from the right side of the box is high and wide to the right. Assisted by Christian Eriksen with a cross following a corner.
45:00 +0:32Corner, Tottenham Hotspur. Conceded by Ben Chilwell.
45:00 +0:31Attempt blocked. Son Heung-Min (Tottenham Hotspur) right footed shot from the right side of the box is blocked. Assisted by Tom Carroll.
43:13Attempt missed. Yohan Benalouane (Leicester City) right footed shot from outside the box misses to the right following a corner.
43:08Attempt blocked. Daniel Drinkwater (Leicester City) right footed shot from outside the box is blocked.
42:30Corner, Leicester City. Conceded by Kevin Wimmer.
41:06Attempt missed. Leonardo Ulloa (Leicester City) right footed shot from outside the box is close, but misses the top right corner. Assisted by Gökhan Inler.
38:48 Goal scoredGoal! Goal! Leicester City 0, Tottenham Hotspur 1. Son Heung-Min (Tottenham Hotspur) right footed shot from the right side of the box to the top right corner. Assisted by Tom Carroll.
35:50Attempt missed. Tom Carroll (Tottenham Hotspur) left footed shot from outside the box misses to the right. Assisted by Nabil Bentaleb.
34:18Attempt missed. Erik Lamela (Tottenham Hotspur) header from the centre of the box is too high. Assisted by Ben Davies with a cross.
33:56Attempt blocked. Christian Eriksen (Tottenham Hotspur) right footed shot from outside the box is blocked. Assisted by Kyle Walker.
32:00Attempt blocked. Nacer Chadli (Tottenham Hotspur) right footed shot from the left side of the box is blocked.
30:04Attempt missed. Ben Davies (Tottenham Hotspur) left footed shot from outside the box misses to the right. Assisted by Kyle Walker following a corner.
29:34Corner, Tottenham Hotspur. Conceded by Ben Chilwell.
28:22Hand ball by Son Heung-Min (Tottenham Hotspur).
27:42Attempt saved. Gökhan Inler (Leicester City) right footed shot from outside the box is saved in the top right corner.
26:34Foul by Tom Carroll (Tottenham Hotspur).
26:34Ben Chilwell (Leicester City) wins a free kick in the attacking half.
25:12Corner, Tottenham Hotspur. Conceded by Demarai Gray.
22:43Attempt missed. Ben Davies (Tottenham Hotspur) left footed shot from outside the box is too high. Assisted by Nabil Bentaleb following a corner.
22:13Corner, Tottenham Hotspur. Conceded by Yohan Benalouane.
19:18 BookingBooking Ben Davies (Tottenham Hotspur) is shown the yellow card for a bad foul.
19:14Foul by Ben Davies (Tottenham Hotspur).
19:14Nathan Dyer (Leicester City) wins a free kick on the right wing.
17:23Offside, Tottenham Hotspur. Tom Carroll tries a through ball, but Nacer Chadli is caught offside.
16:10Foul by Tom Carroll (Tottenham Hotspur).
16:10Daniel Drinkwater (Leicester City) wins a free kick on the left wing.
14:13Kyle Walker (Tottenham Hotspur) wins a free kick in the defensive half.
14:13Foul by Leonardo Ulloa (Leicester City).
12:59Attempt missed. Christian Eriksen (Tottenham Hotspur) right footed shot from the left side of the box misses to the right. Assisted by Son Heung-Min.
4:27Foul by Erik Lamela (Tottenham Hotspur).
4:27Demarai Gray (Leicester City) wins a free kick on the left wing.
0:51Foul by Erik Lamela (Tottenham Hotspur).
0:51Gökhan Inler (Leicester City) wins a free kick in the attacking half.
0:00First Half begins.
0:00Lineups are announced and players are warming up.
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