Mikel Arteta has admitted he's "worried" about Gabriel after the Arsenal defender was forced off with an apparent hamstring injury in their 2-1 Premier League win over Fulham on Tuesday.

The Brazil center-back pulled up while running back toward his goal as Fulham launched a counterattack. When play eventually stopped, he dropped to the ground and shook his head in a signal that he needed to be replaced.

Gabriel eventually came off in the 16th minute, replaced by Jakub Kiwior, and his availability for next week's Champions League meeting with Real Madrid has been thrown into doubt.

Another Arsenal defender, Jurriën Timber, also went to ground in the first half after a clash with Raúl Jiménez. The Netherlands international was able to carry on playing, but was substituted in the 77th minute.

"I'm worried, because he never wants to come off -- and he had to," Arsenal boss Arteta said of Gabriel.

"He's not really sure how big it is or what it was exactly, but he could not continue. He felt something [in his hamstring], yeah.

"There's a week [until Real Madrid], but I would say today the way he is normally, it's difficult.

On Timber, Arteta added: "Timber was struggling yesterday but we lost Ben [White] as well. He did a big effort to try to play but he could not continue."

Arsenal, who are second in the league and started the Fulham match 12 points behind Liverpool, have a two-legged quarterfinal meeting with Madrid this month. The first leg is at the Emirates Stadium on April 8.