After out-playing Aston Villa to win 2-0 on the opening day of the season the Latics were caught out by a pumped up Wolves team on Tuesday, conceding a sixth-minute goal which cost them dearly.

With United slipping to a shock defeat at Burnley 24 hours later Martinez knows his players cannot afford to be similarly off their game against the Barclays Premier League champions.

"We will learn a lot from the Wolves game but this is a totally different scenario," he said.

"We came in to play at home (against Wolves) with great expectations after the result at the weekend and that is something new for us.

"Physically we need to recover but also mentally. The players need to get back to the levels that they need to be able to enjoy their football and perform.

"Obviously Manchester United are one of the best teams in the world and they will test us.

"It is important we are as good as we can be and we couldn't be like that against Wolves and that is disappointing and frustrating.

"But you learn a lot more from these situations and it is going to be a great lesson for us to keep improving.

"We can't afford to fall behind early against United because it then becomes a very long game.

"The margin of error is the biggest difference in the Premier League but it is the same as anything, you have to be at your best as a team otherwise you are going to find it very difficult."

Tomorrow sees the return to the DW Stadium of winger Antonio Valencia, who moved to Old Trafford for a reported £17million in the summer.

However, Wigan chairman Dave Whelan is hoping Michael Owen does not choose the occasion to prove a point after earlier this summer questioning whether the former England striker had the "bottle" for the Premier League any more.

Whelan said in June he would not try to sign the player, then a free agent after leaving Newcastle, because the club could not afford his wages and he questioned his appetite for top-level football after a series of injuries.

But, now manager Sir Alex Ferguson has given him a chance at United, Whelan admits the player may yet have something to offer.

"I have said 'is Michael Owen fully fit after his injuries?' but when Sir Alex went to sign him I thought that was a shrewd move," added the Latics chairman.

"In the box there is nobody quite like him. I know he's not scored any yet but I think he'll get United 15 to 20 goals this season."

Whelan is also prepared for a backlash from United after their humbling at Turf Moor.

"Manchester United will be up for it on Saturday like we will," he said.

"We have both just been mugged by teams that have come up so it is going to be a tough match.

"We have competed very well with them in the league recently, we pushed them very close in losing 1-0 at Old Trafford last season and here we were winning 1-0 with 20 minutes to go.

"I think it will be a good game."