Per Mertesacker has urged Arsenal to repeat their FA Cup victory over Manchester United this weekend and banish fears of another Champions League play-off.

The Gunners’ hopes of securing second place in the Premier League were derailed by Monday’s 1-0 defeat at home to Swansea – the first time they had lost in any competition since February.

And even a third-place finish would be under real threat if Arsenal were to lose again at Old Trafford, the scene of their FA Cup quarter-final success in March, on Sunday (kick-off 4pm).

The Gunners captain said: “We won there once and it’s possible to do that twice per season, so we’re very positive and looking forward to it. We are still in a good mood and a good level of confidence.

“Most important will be the duels in midfield around Marouane Fellaini –that is a major part of their game and Francis Coquelin did really well last time.

“We need to try and control this. It’s not going to be easy, but we want to keep the ball as much as possible, get the ball in their half and break – that is what we did last time and we did it really well.

“Overall we keep going and that’s the most important thing when you lose. We need to get the momentum going again and we are ready for any opponent.”

The Gunners do have a game in hand on second-placed Manchester City, but they are still three points behind and bear an inferior goal difference to their rivals.

And Mertesacker acknowledged that his side must do their utmost not to slide into fourth place and subject themselves to a two-legged qualifying tie for the Champions League in August yet again.

“We put Swansea under pressure and had massive opportunities to score,” added the Arsenal defender. “All of a sudden they scored out of nothing, so that was a big punishment for us.

“We didn’t give too many chances away but, if you have opportunities in the Premier League and don’t score, then you battle just for the fourth place and not the second.

“When you look at the schedule, the [summer] break will not be that much, even for non-international players. We have players in the European Under-21 Championships and in the Copa America, so we’re trying to avoid that.”