Arsene Wenger admits Arsenal's bid for a top-four finish in the Premier League is in danger of ending in disaster unless his players toughen up. Wenger's side are seven points adrift of fourth-placed Tottenham after slumping to a 2-1 defeat at London rivals Chelsea and their hopes of qualifying for the Champions League are looking bleak. A week after waving the white flag all too quickly in a 2-0 loss against Manchester City, Arsenal once again paid the price for a nervous start. They were two goals behind within 16 minutes at Stamford Bridge and though Theo Walcott sparked a spirited second-half fightback when he reduced the deficit, Arsenal couldn't turn their possession into an equaliser, leaving Wenger to bemoan his side's lack of killer instinct. "We started the same as against Manchester City. We didn't go for it and didn't defend well," Wenger said. "When you start 2-0 down in the big games it is very difficult. Chelsea played well but we gave them too much room and didn't defend tight enough. "We had a physical problem to get going. There is a psychological ingredient in there for sure as well, because in the last two games we didn't really go for it. "On top of that we were a bit unlucky because I felt it was a free kick for the first goal and the second wasn't a penalty. The referee could have given a yellow card to Ramires [for diving]." With just one win in their last five matches in all competitions, Arsenal are still far too inconsistent to take a top-four place for granted and the prospect of failing to qualify for Europe's elite club competition is giving Wenger cause for concern. "This defeat is very damaging for our position in the league and very difficult to swallow," Wenger said. It was just Chelsea's second home league win under Rafael Benitez and for once the former Liverpool manager, so unpopular with Blues fans, avoided any abuse from the stands. And Benitez took the opportunity to take a swipe at the critics who claimed he would never win over Chelsea's supporters. "People like to talk about stats but they don't have any clue what is going on," he said. "When you have only one striker for a month it is hard to change things around. Now we have two it is easier."