Wojciech Szczesny has described Arsenal's performance in Monday's 2-1 defeat at Fulham as "childish" and he was not referring to Arsène Wenger's post-match whinge. The Poland goalkeeper had to accept a share of the responsibility for the late reverse, having flapped at Bryan Ruiz's corner that led to Steve Sidwell's 85th-minute equaliser. Bobby Zamora scored Fulham's winner in added time.

Arsenal looked jaded in the second half, which Fulham dominated, and they slipped to their sixth Premier League defeat after Johan Djourou's 78th‑minute dismissal. Szczesny suggested that their concentration levels had been sub-standard and he stressed the need to bounce back in the next league game at Swansea City on Sunday week. Before that Arsenal entertain Leeds United in the FA Cup.

"We played 48 hours previously at home to QPR and then we went one man down," Szczesny said. "There were probably some tired legs but we should have kept the concentration and kept the focus and we would have been fine. But I would imagine it was a very childish performance in the end from us.

"It was very confusing. I thought for 85 minutes we defended really well with 11 men and they never looked like scoring and then, when we had to play with 10 men, they looked very dangerous. I'm very disappointed with the result but hopefully we can recover as soon as possible."

Wenger flew into a rage at full-time, accusing Fulham's players of attempting to get Djourou sent off and criticising the referee, Lee Probert, for the "naive" way that he fell for it. The Arsenal manager said Djourou's first booking, for a tackle through the back of Moussa Dembélé, was "not a yellow card" and that the second, when he argued that Djourou had not touched Zamora, had been preceded by a foul on the Arsenal defender Per Mertesacker by Clint Dempsey.

The assertions felt flimsy, to say the least, and the Football Association has been happy to let them drift without censure. Wenger was on safer ground when he said that Gervinho should have had a penalty for a trip by Philippe Senderos.

There was anger in the Arsenal dressing room that Zamora had made the most of Djourou's challenge, even though the defender had been caught the wrong side of him on the edge of the penalty area. "Johan's said that he barely touched him and the guy seemed to go down very easy," Szczesny said. "Plus, I had the ball in my hands already, which doesn't help."

But the Fulham defender John Arne Riise highlighted how Djourou had already got away with tackles that might have been deemed worthy of bookings. "He had three tackles in quite a short time. I thought it should have been a yellow card in the attack before that. The referee made the right decision. We never go out to get someone sent off. That is not fair play and we never do that."

Riise was delighted that Fulham's fitness stood the test of the 90 minutes. Like Arsenal, they had played on New Year's Eve – the 1-1 draw at Norwich City. "We're quite a fit squad and we love to work hard. We were a bit stronger than them at the end. When Theo Walcott and Gervinho went off that was a tactical change because they knew they were struggling. We are looking strong and fit and it was a massive win for us."