Luiz, who returned ahead of schedule from a knee injury against Newcastle on Sunday, limped off with what looked to be a hamstring injury early in the second half at St. James’ Park as Arsenal wion 2-0.
Arteta will have been relying on Luiz’s experience for their crucial semi-final second leg against Villarreal on Thursday.
Arsenal’s hopes of Champions League football hang on winning the Europa League and the Gunners trail former manager Unai Emery 2-1 from the first leg in Spain.
Arteta revealed before the game at Newcastle that key duo Alexandre Lacazette and Kieran Tierney are not expected to be involved on Thursday.
“It’s incredible the amount of injuries we’ve had,” Arteta told Sky Sports when asked about Luiz’s injury. “We’re losing big players.
“There is nothing we can do about it. It’s a shame because David had made a big effort to be available again after surgery on his knee and today it looks like we lose him again.”
The win at Newcastle kept Arsenal’s slim hopes of qualifying for Europe via the Premier League alive, and Arteta said anything is possible across the four final games of the season.
“This game showed our focus is still there in the Premier League,” he said. “We believe that anything is possible if you’re picking up points and we wanted to put bad results out of the way.
“We had a great attitude, some moments of real quality and had total control from the start.
“We refreshed the team because we’ve played so many games. Thursday was very demanding but the team was really committed and focussed on this game and that’s why we won.
“We controlled the game and we accelerated it when we needed to. The early goal gave us confidence which we needed after the defeat on Thursday.
“We have to do as well as we can and finish as high as we can.
“You need big performances and we had that today.”