Championship-winning Milwaukee Bucks center Brook Lopez has undergone surgery to address the back injury that has kept him out since the opening game of this season.

The Bucks revealed that the 33-year-old underwent back surgery on Thursday in Los Angeles.

Milwaukee declined to offer a timetable on his potential return to play, but said he will " updates on his rehabilitation progress will be provided as appropriate".

The Bucks' title defence has been impacted by the absence of several players early this season, including Lopez along with Jrue Holiday (ankle) and Khris Middleton (COVID-19) who have missed stretches of games. Milwaukee are currently 14-8.

"He's basically been making very, very slow but little progress from the beginning," Bucks coach Mike Budenholzer told reporters before Thursday's game at Toronto. "We hoped rest and rehab and things like that would solve it and it hasn't."

"We're not going to put a timeline on it, but we're also not going to say he's not going to play this season. We feel good about the surgery today, and he'll begin his rehab and do everything he can to put himself in a position to play for us."

Lopez averaged 12.3 points, 5.0 rebounds and 1.5 blocks for the Bucks in their title-winning 2020-21 season.