Michail Antonio's 90th-minute winner left Leeds still searching for a first Premier League win of the season as they were beaten by West Ham at Elland Road.
In a match that saw 35 attempts on goal, Marcelo Bielsa's side had the better chances in the first half but the visitors grew into the game as excitement turned to nerves among the home fans in a cagey encounter.
Raphinha had opened the scoring for Leeds on 19 minutes with a clinical low finish from outside the area.
West Ham thought they had equalised eight minutes into the second half, but Tomas Soucek's effort was ruled out after referee Kevin Friend checked the pitchside monitor and spotted an Antonio foul on goalkeeper Illan Meslier.
The Hammers eventually found a way through when Jarrod Bowen's shot from inside the box deflected off Junior Firpo and into the back of the net.
In the first minute of injury time, Leeds were caught out on the counter-attack as Antonio knocked the ball past defender Jamie Shackleton before sliding in the winner to push the hosts into the bottom three.
This is only the second time in Leeds' history that they have failed to win any of their first six games of a top-flight campaign - it last happened in 1935-36.
