Olivier Giroud says Arsenal must switch on at set-pieces to keep Manchester United at bay on Wednesday night.

The Gunners were beaten by Robin van Persie's header at Old Trafford earlier this season and were undone by Liverpool's dead-ball deliveries in Saturday's heavy defeat at Liverpool.

Giroud's aerial ability is a major asset to an Arsenal side that - excluding their trips to Etihad Stadium and Anfield - has conceded 15 times in 23 Premier League fixtures. And the Frenchman says concentration will be key tonight.

It will be a big game on Wednesday but I'm very confident about our chances. We want to start the game on the front foot and be determined

"I think we need to understand how we lost at Old Trafford," Giroud told Arsenal.com. "We didn't deserve to lose that game but it's always like that on set-pieces - you have to be completely focused.

"I think Manchester [United] will come to Emirates Stadium and look for the win because they are a bit far away from us in the table. We will be ready for them.

"We really need to win the big games against Man City, Man United and Chelsea as well, teams we play in the next month or so. They are our straight opponents.

"It will be a big game on Wednesday but I'm very confident about our chances. We want to start the game on the front foot and be determined."

Giroud freely admits he was not at his best at Liverpool but he feels strong amid a testing run of five games in 14 days.

"I try to keep focused on my work on the pitch and then try to have a good recovery when I am home," he said. "It's about eating well, sleeping well and taking care of your body.

"I was a bit tired in December after we played a lot of games but in January we had time for a rest. I enjoy playing every three days and we're used to doing that so it's not going to be a problem for us."

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source Chris Harris 12 Feb 2014