The Derry man, who has scored once in three games for United this season, may have to make do with a place on the bench for Ireland's Euro 2012 qualifiers against Russia and Slovakia next month.
"I'm not expecting to start the games but I'll be ready if he needs me," he admitted.
"I'm not really concerned because I think if I start playing for Manchester United every game I'll eventually play for Ireland every game.
"I'm just going to concentrate on getting into the United team. Obviously I'm ready to play when I go away with Ireland. If I don't get picked I'll be on the bench and ready to come on, what else can I do?
"Obviously I'm disappointed with not playing but Paul Green's a good player. He's scored a lot of goals and obviously he's playing every week, which I'm not.
"I can see why Trap (Giovanni Trapattoni) picked him ahead of me. Things like that happen in football so you can either get on with it or sulk about it. I'll be ready to take the chance when he puts me in.
"I would have liked to have been involved a bit more this season but I'm going to have to wait for my chance, like I did last season, and hopefully take it when it comes."