Match ends, Leeds United 0, Middlesbrough 0.
Leeds and Middlesbrough, the top two sides in the Championship table, played out a forgettable goalless draw at Elland Road.
Both teams had taken 13 points from their first five matches but cancelled each other out in a mediocre contest devoid of any rhythm and broken up by a constant stream of niggly fouls.
Middlesbrough went close with Jonny Howson's curling first-half shot, which was kept out by Leeds goalkeeper Bailey Peacock-Farrell, while Britt Assombalonga headed over from a corner.
At the other end, Luke Ayling's header was cleared off the line by Boro's Adam Clayton.
Leeds remain above Middlesbrough on goal difference, while both clubs kept up their unbeaten Championship starts in 2018-19.
Marcelo Bielsa's Leeds had scored at least twice in each of their opening five league games, catching the eye with their intense pressing and quick passing style.
However, Boro managed to limit them to few opportunities on their way to a fifth successive Championship clean sheet.
They had a moment of panic in second-half stoppage time when Leeds were given a free-kick in a dangerous position, but Barry Douglas shot straight at goalkeeper Darren Randolph.
The visitors' main threat came from set-pieces and crosses into the box, but Ryan Shotton and Daniel Ayala sent headers well off target and Leeds otherwise rarely looked like conceding.
Match ends, Leeds United 0, Middlesbrough 0.
Second Half ends, Leeds United 0, Middlesbrough 0.
Attempt saved. Barry Douglas (Leeds United) left footed shot from outside the box is saved in the top left corner.
Aden Flint (Middlesbrough) is shown the yellow card for a bad foul.
Patrick Bamford (Leeds United) wins a free kick in the attacking half.
Foul by Aden Flint (Middlesbrough).
Attempt blocked. Samuel Sáiz (Leeds United) right footed shot from outside the box is blocked. Assisted by Mateusz Klich.
Corner, Leeds United. Conceded by Ryan Shotton.
Substitution, Leeds United. Stuart Dallas replaces Jack Harrison.
Liam Cooper (Leeds United) wins a free kick in the defensive half.
Foul by Britt Assombalonga (Middlesbrough).
Offside, Leeds United. Bailey Peacock-Farrell tries a through ball, but Patrick Bamford is caught offside.
Substitution, Leeds United. Patrick Bamford replaces Kemar Roofe.
Pontus Jansson (Leeds United) wins a free kick in the defensive half.
Foul by Daniel Ayala (Middlesbrough).
Corner, Middlesbrough. Conceded by Bailey Peacock-Farrell.
Attempt saved. Daniel Ayala (Middlesbrough) header from the right side of the six yard box is saved in the bottom right corner. Assisted by Muhamed Besic with a cross.
Delay over. They are ready to continue.
Substitution, Leeds United. Pontus Jansson replaces Gaetano Berardi because of an injury.
Delay in match Gaetano Berardi (Leeds United) because of an injury.
Corner, Middlesbrough. Conceded by Luke Ayling.
Corner, Middlesbrough. Conceded by Gaetano Berardi.
Offside, Leeds United. Barry Douglas tries a through ball, but Liam Cooper is caught offside.
Daniel Ayala (Middlesbrough) is shown the yellow card for a bad foul.
Mateusz Klich (Leeds United) wins a free kick on the left wing.
Foul by Daniel Ayala (Middlesbrough).
Attempt missed. Daniel Ayala (Middlesbrough) header from the centre of the box misses to the right. Assisted by Muhamed Besic with a cross following a set piece situation.
Liam Cooper (Leeds United) is shown the yellow card for a bad foul.
Foul by Liam Cooper (Leeds United).
Britt Assombalonga (Middlesbrough) wins a free kick on the right wing.
Foul by Kalvin Phillips (Leeds United).
Ryan Shotton (Middlesbrough) wins a free kick on the right wing.
Gaetano Berardi (Leeds United) is shown the yellow card for a bad foul.
Foul by Gaetano Berardi (Leeds United).
Britt Assombalonga (Middlesbrough) wins a free kick in the attacking half.
Attempt missed. Stewart Downing (Middlesbrough) left footed shot from outside the box is too high. Assisted by Britt Assombalonga.
Attempt blocked. Samuel Sáiz (Leeds United) right footed shot from outside the box is blocked. Assisted by Kalvin Phillips.
Kalvin Phillips (Leeds United) wins a free kick in the defensive half.
Foul by Britt Assombalonga (Middlesbrough).
Offside, Leeds United. Samuel Sáiz tries a through ball, but Ezgjan Alioski is caught offside.