John O'Shea says Manchester United must be wary of a Portsmouth backlash when they travel to Fratton Park on Monday.

United head to the south coast looking for a win to kick-start their title defence following a disappointing opening-day draw with Newcastle.

But their task, at a ground where they always find it hard to get a result, is made even harder by the FA Cup winners' four-goal hammering at Chelsea last weekend.

And, rather than taking advantage of a dispirited outfit, O'Shea fears Portsmouth will be even more determined now.

"It is a tricky enough game anyway but we are aware there might be a backlash from the Chelsea defeat by Portsmouth," said the Republic of Ireland international.

"We have played them a couple of times already in pre-season, which maybe helps a bit, because it is important to get that win.

"The manager has a few more things to deal with with us coming back from international week. But we do not want to give other teams a head-start."

O'Shea is likely to start in central midfield as Michael Carrick is set to be sidelined for three weeks with an ankle injury picked up against Newcastle.

Anderson will return but Sir Alex Ferguson is reluctant to use the Brazilian given he is not due to leave Beijing until Sunday following his stint at the Olympics.

Having come on as a substitute last weekend, it is just the kind of involvement O'Shea loves. And it is a major reason why the Waterford-born player has no desire to leave.

"Hopefully I will be here as long as the manager wants me," said the 26-year-old.

"It is a squad game now and I am happy here doing what I am doing.

"When I get in, it is a case of making sure I do enough to give the manager a difficult decision to leave me out the next time. That is the challenge I face every time I play."

Park Ji-sung will not be considered but Owen Hargreaves will be assessed on Sunday to see whether his tendinitis problem has eased sufficiently to be involved.

It has been another frustrating pre-season for the former Bayern Munich man, who struggled with the same injury last summer.

But at least United are on top of the situation now, leaving Hargreaves confident he can play a major role in the pursuit of honours.

"I would like to think I can play a bigger part this year," he said.

"That is what I am planning on doing anyway."