Arsene Wenger praised Arsenal's commitment and felt they were "a bit unlucky" in their 2-0 FA Cup fifth-round defeat to Sunderland.

Richardson: Scores Sunderland's first

It has been another terrible week for the Gunners, who were all but eliminated from the Champions League in midweek with a 4-0 first-leg defeat at AC Milan, while the best they can hope for in the Premier League appears to be fourth place.

Wenger was not keen to talk about his own future at the club, saying only: "We have to take the criticism on board, stay together and face the critics. The only response in our job is to stay united and fight and focus on the next game.

"It's very difficult tonight to say where it leaves us and what we will do, let's focus to finish well in the championship and fight as well, even if it's a small possibility, in the Champions League."

Wenger had been critical of his players in Milan but felt they had given everything in difficult circumstances against Sunderland after a week that began with a league victory at the Stadium of Light last Saturday.

The Frenchman also argued his side should have had a penalty in the first half when Robin van Persie tangled with John O'Shea but referee Howard Webb was unmoved.

Wenger said: "I think it was a committed performance and we gave absolutely everything that was left in our legs.

"We had three away games in one week and I believe it was a very unfortunate schedule to play away in the Champions League and immediately away again. They were very difficult pitches as well but we fought hard today.

"I felt we were a bit unlucky, it was 100% a penalty for us that Mr Webb missed and their first shot on goal was a goal. Then we had to chase the game and take every gamble and we were caught on the counter for the second.

"We had a lot of possession, didn't create a lot down to fantastic defending from Sunderland, but they left us the ball and ran after it."

Arsenal desperately needed a response after the drubbing in Milan but they only had one clear-cut chance in the whole match, and Simon Mignolet comfortably pushed Gervinho's 28th-minute shot over the bar.

Sunderland's performance was typical of a team schooled by Martin O'Neill, hassling and harrying Arsenal all over the pitch and looking to break quickly when they did get the ball.

The Arsenal defence never looked comfortable and they paid a heavy price in the 40th minute when Johan Djourou let in Craig Gardner and then earned a yellow card for pulling him back.

Sebastian Larsson swung in the free-kick and, although it was headed away by Thomas Vermaelen, Kieran Richardson connected superbly with the half-cleared ball which flew into the bottom right corner with the aid of a slight deflection off Sebastien Squillaci.

James McClean could have added a second goal before half-time but poked a close-range effort just wide, and after the break Arsenal huffed and puffed before the tie was put beyond them 12 minutes from time.

Stephane Sessegnon set up Larsson with a driving run and the winger's shot rebounded off the inside of the right post and in off the legs of Alex Oxlade-Chamberlain.

The Black Cats had taken the lead against Arsenal last weekend before conceding a leveller and then succumbing to a late Thierry Henry strike, and boss O'Neill felt his side's lack of a midweek game had been an important factor.

"I think that helped us immensely," he said. "We had lots of energy, if anything we were getting stronger as the game was going on. The last 15 minutes of last week I thought we were really tired but I think the advantage swung our way this week."

Sunderland, whose only major post-war trophy came when they beat Leeds in the 1973 FA Cup final, now go forward to Sunday's quarter-final draw.

O'Neill said: "I'm really, really delighted for everybody concerned with the football club and the players in particular. I thought they were excellent today, not just working hard but when we had the ball.

"There's plenty of self-belief about the team, that's getting stronger and I think they feel as if they can win matches, which is great."