Arsenal boss Mikel Arteta is considering tapping into the transfer market to bolster his squad following a “significant injury” to Gabriel Jesus.

Arsenal’s big pre-season signing had to leave the World Cup early because of a knee injury he got when Brazil was shocked by Cameroon.

Jesus had surgery, and Arteta said Thursday that he doesn’t know when Jesus will be back, but that his injury is bad enough that the Premier League leaders will have to look for a new player next month.

“I never gave a date. I said that we don’t know. It’s going to take some time for sure,” Arteta said of Jesus.

“He’s gone through surgery and that tells you the extent of the injury, so we will be in the market and we will assess the biggest opportunities that we have.

“We are going to be active and active means we are looking to strengthen the team.”

“This squad still doesn’t have the luxury of not maximising every single window. We have to do that because it’s really important but then we have to get the right profile. It has to be the right player to take us to the next level.”

After the World Cup break, Arsenal will play at home against London rivals West Ham on December 26. At that time, Arsenal will be five points ahead of Manchester City, who is the current English champion.

Jesus has been a big part of their success in the Premier League since he moved there from Manchester City. He has scored five goals and set up six others, even though he hasn’t scored in his last 10 club games.

“Obviously a huge blow with Gabriel Jesus and his injury,” Arteta added on Thursday.

“We’ll miss him for a period of time. The season has challenges, that’s a challenge we have to overcome, but if you’re going to be at the top there’s going to be those challenges.”

Jesus is likely to be out for a long time, but most of Arsenal’s World Cup players are expected to play against the Hammers.

William Saliba will return to training on Friday, and Arteta will decide late in the week whether or not to play the French center-back. However, both Emile Smith Rowe (groin) and Reiss Nelson (muscle) are out.

“Some (World Cup players) came home earlier than expected and they were buzzing to be back and part of it,” said Arteta.

“I feel a really good energy around the place. They have got straight away into the rhythm and what we want.”