Arsene Wenger's side will attempt to bounce back following Wednesday's frustrating 2-0 first leg defeat to the German champions in the last 16 of Europe's elite club competition.

The loss, compounded by the first half dismissal of goalkeeper Wojciech Szczesny and an early penalty miss by Mesut Ozil, leaves Arsenal facing a daunting task in the second leg in Munich if they are to reach the quarter-finals.

But Gunners centre back Mertesacker insists his team-mates cannot afford to dwell on that as they attempt to maintain their standing in the Premier League title race.

Arsenal currently lie second, a point behind leaders Chelsea and two points ahead of Manchester City who have played a game less.

With such fine margins separating the leading group, a home slip against an improving Sunderland side is likely to prove costly, and will do nothing to repair the battered morale at the north London club.

And Mertesacker said: "We will concentrate on Saturday now, because we are going through a period with a lot of games.

"We will switch off from the Champions League now, and then switch on again for the Premier League on Saturday.

"We need that because we have played a lot of games. Our team has great spirit and will come back from this.

"The next tie against Bayern is not now for a few weeks, so a couple of days before that game we will think about it."

Arsenal's Germany midfielder Ozil came in for heavy criticism following the Bayern defeat and was involved in an on-field argument with team-mate Mathieu Flamini.

Wenger has defended the performances of the club's record signing in recent weeks.

But the Frenchman is likely to make some changes to his midweek starting line-up and bring in fresh legs, particularly as his side were forced to play more than half the game with 10 men against a Bayern side that dominated possession.

Wenger must also decide whether to restore Olivier Giroud to lead the attack after handing the main striker's role to the inexperienced Yaya Sanogo in the last two games.

Meanwhile, Sunderland manager Gus Poyet has confirmed Steven Fletcher is fit for his side's League Cup final against Manchester City.

But he won't risk the Scotland international from the start against title-chasing Arsenal.

Fletcher is set for a place on the bench at the Emirates Stadium after shaking-off a persistent Achilles problem.

The former Wolves and Burnley forward hasn't started a game for almost a month due to an injury it was feared would require season-ending surgery.

But the 26-year-old has responded to treatment to put him in contention to face Manuel Pellegrini's men at Wembley on March 2.

"Steven is fit. If you are asking if he is ready for 90 minutes at Arsenal, then no, I am not going to lie," Poyet said.

"It would be a massive risk to play from the beginning, and Saturday is an important day to look at him and to define how we can use him."

Poyet admits he faces a tough choice in central midfield between Liam Bridcutt and Lee Cattermole.

Bridcutt has been preferred to Cattermole since his �2.5 million move from Brighton last month.

However, Bridcutt is cup-tied and misses out on next month's final.

Poyet is yet to make the call on which one of the pair will face the Gunners, and admitted: "That is the biggest decision of the week. Have I made it yet? No.

"It is probably the biggest decision I have got and we need to be really smart."