Arsenal manager Arsene Wenger says Chelsea's 11-point at the top is a concern for the Gunners.
The Blues battled their way past Crystal Palace on Saturday afternoon and lead the table on 22 points with Arsenal lying sixth with only 11 points from eight games.
"I think the performance was quite good but we put ourselves in trouble because we gave two goals away," Wenger said during his post-match press conference.
"We put our heart and effort in until the last second and I cannot fault the effort, the spirit and the work rate of the team. I'm quite respectful for that.
"The first goal is for the referee. The second one is for us and I said that.
"[Jack Wilshere] is well [and can feature in mid-week].
"Of course [it's a concern to be so far from the top of the table].
"I cannot say it's not a concern, it's a big concern because the other teams have won their games and we haven't. I cannot say it's not a big concern."