Doncaster came from behind to win 3-1 at Coventry and keep the Sky Blues firmly in a relegation battle.Coventry took the lead in the fourth minute when skipper Jim O'Brien, back from from injury, slid a pass through to Dominic Samuel.The on-loan Reading striker took the ball in his stride and calmly fired into the bottom corner past Doncaster goalkeeper Stephen Bywater.The home team had chances to extend their lead in the first half and were left to rue them when Doncaster drew level in the 50th minute.Veteran midfielder Richie Wellens stole into the Coventry box and managed to wriggle clear before firing low past home goalkeeper Lee Burge.Jonson Clarke-Harris took advantage of a mistake by Chris Stokes in the 72nd minute. Burge saved his first shot, but the striker nipped in quickest to steer home the rebound.Another error, this time from Aaron Martin in the 84th minute, allowed Doncaster to seal the points as he let Curtis Main pinch the ball inside the penalty area to lay it on a plate for Harry Forrester to slide home.