Arsenal boss Mikel Arteta said on Wednesday his side's poor form in the Premier League is a constant source of worry and that he was trying to get to the root of the problem for its failure to score in tight games.

Arsenal is 14th in the standings having lost four of its last six games, with three losses coming against teams who beat it by a single goal.

Arteta said Sunday's 2-1 loss to Wolverhampton Wanderers left a "really bad taste" and the Spaniard is set to make changes for Thursday's Europa League game against Rapid Vienna.

"I'm really worried about the results and the margins that we are losing games," Arteta told reporters.

"When we analyse the games afterwards - 'why are we losing these games when they are so tight?' - there is a reason that sometimes you win it and sometimes you lose it, but we need to recover.

"Sometimes it's a lack of confidence in certain moments because we conceded as well... Then obviously the goals we need to score to win football matches more consistently."

Arsenal has already qualified for the knockout stages with four wins.

David Luiz is ruled out after his clash of heads with Wolves striker Raul Jimenez but Arteta said the defender could return on Sunday when Arsenal faces local rival and league leader Tottenham Hotspur.

"I think he will be fit to play if the scar is healing properly and he's comfortable heading the ball," Arteta said.

Arteta added that Thomas Partey has started training separately but he was unsure if the midfielder would be fit for the derby.

Thursday's match will mark the first time a Premier League team welcomes back fans to the stadium amid the COVID-19 pandemic, with 2,000 being allowed to attend.

"It's going to be extraordinary to have them back. It's going to feel strange," Arteta added. "I'm feeling sorry for thousands of fans who want to make it and won't be able to be there." (