Ben Foster has revealed that being left out of the Manchester United starting line-up is getting too much for him.

Foster could be forced to move away from the Red Devils to give his ailing career a much-needed jumpstart if he is to make it to the World Cup in South Africa.

The frustrated keeper is currently third choice for Man United and is shocked that Fabio Capello has retained his faith in the 26-year-old shot-stopper.

He said: "I'm not playing at United, which makes it a lot more difficult for myself. It's very, very disheartening.

"Ideally, I'd like to be playing. That's not happening but the England boss is giving me a few chances.

"I'm really grateful for the chances and when I get the chance I've just got to show what I can do and hopefully that will keep me in the squad.

"It's difficult at United with Edwin van der Sar. He's one of the best keepers in the world. It's as simple as that.

"You can't go knocking on the manager's door and say he's not doing his job, because he is.

"It was a bit out of the blue to be picked, to be honest. I know that I played the last qualifier, but wasn't expecting it. But I think I did well in training and thankfully the boss stuck with me as well.

"I'm third choice for Manchester United at the moment yet I'm playing for my country.

"I can't go saying that I want to leave or anything like that, I'll see what happens. You never know in football, do you?"

Foster deputised for Van der Sar when the latter injured his hand.

The former Stoke City custodian took in Chelsea, Arsenal, Tottenham and Manchester City to start the season, but has since fallen on the wayside, to the extent that he's even behind Tomasz Kuszczak.

Foster started for England in their final World qualifier, a 3-0 victory for the Three Lions, and was heavily involved against Brazil over the weekend.

The goalkeeper was fortunate to only see yellow when he brought down Nilmar in the area.

However, Foster reveals that Capello is encouraging him with call-ups for England, and he added: "I've not been on the bench lately and you have to keep your head up, keep working hard in training.

"And I'm really thankful for Fabio Capello giving me a chance.

"The World Cup is a big thing, it's everything. A footballer wants to go to the World Cup, it's as simple as that. It's very disheartening not being on the bench.

"I thought I started off well at United this season. There was a period of about two or three games where I made a few mistakes.

"There was the Man City game, a few days later we played against Sunderland and people blamed me for the second goal against Sunderland.

"They were the only mistakes I made though, in my opinion. It was disappointing to lose my place in the team.

"But before that, I thought I was doing fairly well. You can't let it get you too down, especially not with so many games coming up.

"You've got them coming up every other day, almost, playing two or three times a week. You have to just move on. If you let it get on your mind then it will affect you."

Foster concedes that he was only lucky not to be given his marching orders against Brazil.

He added: "I thought I was a definite goner.

"But the ref saw it as a friendly, he gave the decision and I was happy to stay on the pitch.

"We knew it was going to be a difficult match and it's so hot and humid, it's hard to get your breath.

"South American teams will be a lot more used to it but we gave a good account of ourselves.

"We've got a depleted squad and I don't think 1-0 flattered us too much. They had a lot of possession but didn't make many chances."