Forest Green attacker George Williams could be out 'for a while' after injuring his ankle against Tranmere Rovers on Good Friday. 

Williams was substituted at half-time as a result and was replaced by Dayle Grubb. 

The injury occured in the opening stages of the game and Cooper revealed the Welshman is set for a spell on the sidelines. 

"He fell off the uneven part which is really dangerous and twisted his ankle so he's going to be out for a while with that," Cooper said. 

 "He did it in the first minute of the game which was a blow. 

"We have a small squad but we've got quality waiting to come in." 

Junior Mondal scored the only goal of the game as Forest Green edged closer to confirming their play-off place. 

Rovers are five points off third with three games to go out and have a chance, albeit a slender one, of earning automatic promotion. 

Cooper's men host Cambridge United on Monday and the Rovers boss insists their attentions are solely on the game. 

"I am totally focused on Cambridge and putting something into place for the boys to make sure we get three points," he added.