Mark Cooper has revealed there will only be six Forest Green substitutes on the bench for tomorrow's Emirates FA Cup first round tie at Oxford United.

The forward was forced off during Wednesday night's Checkatrade Trophy defeat to Arsenal Under 21s and has been ruled out of Saturday's cup tie as a result.

The 20-year-old joins Liam Shephard and Lee Collins on the sidelines which has left Cooper's squad depleted but the boss isn't too concerned with the lack of numbers.

"Pearce is not fit," he confirmed. "We'll have six subs on Saturday.

"We can only play 11 players and use three subs so we've got enough players and the players who get on the pitch tomorrow will be ready."

The Rovers boss has a few decisions to make ahead of tomorrow's clash. James Montgomery made some crucial saves against Arsenal as he looks to push Robert Sanchez for a starting berth while Cooper has tweaked his defensive line in recent matches, switching between a three and four.

Cooper confirmed he has made his mind up on who plays in goal and the system he'd deployed but gave no indication on the personnel.

"I've made my mind up," Cooper said. "You've have to have that competition. We've got three good goalkeepers.

"Lewis (Thomas) is on loan at Yate Town, he's kept so many clean sheets and they're building a statue of him at Yate because he's been that good.

"At the back, I have no dilemma and I know what I'm going to do tomorrow."

Cooper insists Oxford are the favourites despite their lowly league position in League One and he's expecting a difficult contest whichever line-up the U's put out.

"They have a good squad and some good players," Cooper commented. "I saw them at Wycombe the other night and they rotated the squad and the boys who came in were really good so whatever team they put out will be tough for us but we're looking forward to it.

"It's a free hit for us, the expectation will be on Oxford being a big club in League One so we'll try and use that but however you dress it up you have to go there and play well.

"We've been dealt a tough tie but there has to be some upsets along the way and lets hope we can play really well and cause one."

A draw would mean the tie goes to a replay back at the New Lawn which could be a bit of a nuisance given Rovers' injury list but the manager feels it wouldn't be the end of the world if it keeps Forest Green in the hat.

"If you go to a league one team and draw then bring them back here we'll take it," Cooper said.

"A replay is better than nothing, so we'd take it. I'm sure Karl Robinson we'll be thinking the same that he'll want it done on the day so lets hope we can do that and be on the right side of it."