London - Cheikhou Kouyate's dismissal proved the turning point as West Ham United's charge towards a Premier League top-four finish was slowed in a 2-2 draw with Crystal Palace on Saturday.
After Damien Delaney had punished a mistake by Adrian to put Palace ahead in the 15th minute, West Ham equalised through Manuel Lanzini and then went ahead courtesy of another glorious free-kick from Dimitri Payet.
But Kouyate was shown a straight red card by referee Mark Clattenburg for a high foot on Dwight Gayle in the 67th minute and eight minutes later Gayle pounced on an error by Angelo Ogbonna to equalise.
Slaven Bilic's West Ham are now three points below Manchester City, who occupy the fourth and final Champions League qualifying berth, with seven matches of the season remaining.
Palace remain seven points above the relegation zone, but although they are now without a win in 14 league games, manager Alan Pardew will have drawn encouragement from their second-half fightback.
With Emmanuel Adebayor sustaining a knock on international duty with Togo, Bakary Sako started up front for Palace and it was his free-kick that led to the opening goal.
Sako's cross appeared to be drifting away from danger, only for West Ham goalkeeper Adrian to palm it back into play, and Delaney headed home from a narrow angle.
It was the first goal West Ham had conceded at home in the league since January, but they quickly composed themselves and equalised three minutes later when Lanzini rifled in from Diafra Sakho's knock-down.
The wind in their sails, West Ham twice went close to taking the lead, only for visiting goalkeeper Wayne Hennessey to thwart first Sakho and then Payet.
Jason Puncheon squandered a glorious chance to put Palace ahead when he miscued from Pape Souare's cross, before Sakho headed over at the other end after Hennessey failed to claim a Payet corner.
Payet's set-pieces have been integral to West Ham's fine form and he gave another display of his skill with a dead-ball four minutes from half-time by arcing an inch-perfect free-kick into the top-right corner.
Hennessey prevented Lanzini from swelling West Ham's lead, before Aaron Cresswell produced a brilliant goal-line clearance to thwart Sako at the other end after Kouyate's back-pass had sold Adrian short.
It was almost a horror moment for Kouyate and moments later the Senegalese midfielder found himself trudging from the pitch after being shown a straight red card for a challenge on Gayle.
Palace now had the momentum and they duly equalised when Ogbonna made a hash of clearing Souare's cross and Gayle steered the loose ball home.