Former Arsenal defender Sol Campbell has warned that his old side must spend big in January.
The Gunners have a five point lead at the top of the Premier League over Manchester City.
However, Campbell believes that given City's ability to put together winning runs, and Arsenal's thin squad, the Gunners must keep investing.
Asked about the season so far during an event in Turkey, Campbell explained: “Well, the season is not over. I think Arteta is doing very well and everything has gone well, but you have to evaluate it after the full season.
“It is evident that, after a season and a half where things were not going well with him and he was criticized, they could have sacked him. But they stayed with him and now they are reaping the rewards of him.
“There is still a long way to go in the Premier League and Manchester City are slowly catching up, so it will be interesting to wait until the end of the season. I hope they stay calm and invest just enough to help them."
“For example, Joao Felix, was a good option, but he has gone to Chelsea," the former central defender added.
“I would have liked him to end up at Arsenal. But yeah, that's what they have to do. To get to the top and give it that push, you need those extra players to make a difference.
“And you can't let those players escape because then there are injuries. We have some good players. (Eddie) Nketiah is doing well, scoring goals, but I think Arsenal need a little more just in case.
“Before this window closes, we need to get a little help to get through this and compete with Manchester City, who are tightening up there now."