Arsenal suffered a meltdown late on Sunday to absorb a 2-1 upset loss to Swansea City at Liberty Stadium in Wales.
Alexis Sanchez put Arsenal ahead as he scored the first goal of the match in the 63rd minute, but they allowed Glyfi Sigurdsson to score the equalizer off a free kick in the 75th minute.
Three minutes later, Bafetimbi Gomis netted a powerful header to put Swansea City ahead. Arsenal desperately tried to score another goal, but Swansea City managed to hold en route to the upset win.
"I think it's difficult to explain how we lost the lead as we were in control and they didn't give up," Arsenal boss Arsene Wenger said after the game via ESPN FC. "I thought we lost some decisive challenges in the middle of the park in the last 20 minutes and we paid for that, and that's where we lost the battle."
With the win, Swansea City overtook Arsenal in the English Premier League table with 18 points against the Gunners' 17 points in 11 matches.
Wenger said after the match that he is convinced Arsenal won't have a chance to win the title this year if they will continue dropping winnable games. On Tuesday, Arsenal built a 3-0 lead, but Anderlecht managed to force a 3-3 draw.
"We have to live in the realistic world. In football you have to win the games you can win and today was one," Wenger added. "If you want to challenge for the Premier League you have to be a bit more realistic than we were today."
When asked about the title favorite this season, Wenger said that Chelsea, barring any major collapse, will win the title convincingly, pointing out that no team is capable of challenging the Blues this year.
"Look at the season and Chelsea are on course for 105 points," said Wenger, whose team is 12 points behind the Blues. "Look at the number of points they have today and if they keep that up nobody will touch them, that's for sure. It doesn't look like anybody is capable of challenging them at the moment. There's no obvious reason but they have had a good start and as long as you don't lose you don't question yourself."