Arsene Wenger admits "tough" top-four challenge.

Arsenal manager Arsene Wenger has admitted that his side face a "tough" challenge as they battle to finish in the Champions League spots. Arsenal slipped to a 2-1 defeat to Chelsea at Stamford Bridge on Sunday, a result which leaves them seven points behind fourth-placed Tottenham - albeit with a game in hand.

And the Frenchman believes Arsenal must improve in the coming weeks if they are to qualify for the Champions League again this season.

Wenger told reporters: "We have lost two big games in the last week, and that’s very damaging for us. We can’t drop points any more if we want to be in the top four. That’s a concern.

"We have fantastic quality and spirit, but come into the game when we are 2-0 down. That is very difficult in the big games and at the moment that is worrying for us.”

The 63-year-old also bemoaned his side's poor start against the Blues, a factor which he believes was the main reason for defeat.

"We were stretched, we gave Chelsea far too much room to play and we didn’t defend tightly enough," Wenger continued.

"We didn’t make enough of our chances, which is why we lost. It’s very damaging for our league position and difficult to swallow.""It will be a tough challenge for us to make the top four," said Wenger. "We need to learn to be much more efficient with the quality of game we use.

"Once again we didn't start on all cylinders. We had the first chance in the game, and didn't take it.

"Once we were 2-0 down we came back with a great second-half [performance] and a great spirit. We rushed our decisions in the final third and didn't make enough of our corner and free-kicks in the end."

However, Arsene Wenger criticised referee Martin Atkinson following his side’s 2-1 Premier League defeat to Chelsea.

“The referee gave a lot of free-kicks today, and some much less than the Coquelin one. It’s frustrating.” He told Sky Sports.

“It doesn’t mean we should have conceded the goal but, in the big games, these decisions have big implications.”

“We only came into the game when we were 2-0 down, that’s worrying.”

The loss to their London rivals made it back-to-back Premier League defeats for Arsenal, and Wenger admitted that his team’s form is a concern:

“We have lost two big games in the last week. That’s damaging for us. We can’t afford to lose more points. It’s a concern.

Arsenal host West Ham United in the Premier League on Wednesday.