Arsenal are looking for a player to take them to the "next level" in the January transfer window after losing Gabriel Jesus to injury, says manager Mikel Arteta.

The Gunners entered the World Cup break five points clear of champions Manchester City at the Premier League summit, leading some to tip them as contenders for a first top-flight title since 2004.

Striker Jesus has played a key role for Arsenal this season, but he underwent surgery earlier this month after suffering a knee injury during Brazil's World Cup campaign.

With reports suggesting Jesus could be absent for three months, Arteta is targeting reinforcements – though he will only move for the ideal player. 

"I never gave a date on Jesus – it will take some time, for sure. He's gone through surgery," Arteta said at a press conference to preview Monday's meeting with West Ham.

"We have to be active, we're looking to strengthen the team. This squad does not have the luxury of not maximising every transfer window. 

"It has to be the right player. We need a player that will have an impact and take us to the next level.

"We know where we are in terms of the squad and numbers. We'll be extremely cautious about what we want to do in the window."

Arteta also revealed he had face-to-face contact with the club's hierarchy during the World Cup break, in order to plan for what will likely be a congested second half of the season.

"We are always connected, and that relationship is getting stronger and stronger. It's a very special relationship right now," he said.

"The ambition is there so it's very positive to spend time together. It was spare time, so it was useful to do it in that period.

"We've done our work but the second part of the season will be very different. Matches will come very fast with big congested periods so we have to have a fit, healthy squad to maintain the level that we want.

"There are new coaches and new owners around, so the window will be interesting and we have to be active on it too."