James Coppinger earned Doncaster a precious point at West Ham as Sam Allardyce's team slipped further behind Championship leaders Southampton.
Kevin Nolan tapped in on nine minutes to give the Hammers an early lead.
But the visitors were inspired in the second half by El-Hadji Diouf, who set up Coppinger to equalise late on.
The Senegal winger could have won it when he tested Rob Green but the draw moves second-from-bottom Doncaster level on points with Coventry.
West Ham remain second in the table, three points behind the Saints, but they are level on points with third-placed Reading, who beat Leicester.
They thought they had the perfect start in the first minute when Ricardo Vaz Te had the ball in the net but the Portugal striker was adjudged to have fouled full-back Pascal Chimbonda.
Just a couple of minutes later, Carlton Cole rattled the bar with a vicious strike and it looked as though the Hammers were set to run away with the game when Nolan poked home from close range.
But Doncaster got back into the game when Simon Gillett steered the ball to Coppinger, who made no mistake with his finish.
The relegation-threatened side could have won it late on when Coppinger set up Diouf, but the former Liverpool, Bolton and Blackburn man was unable to get a clean connection on the ball and West Ham keeper Green turned the ball away.