Petro participated in most of the practice and is a game-time decision for Tuesday night's game against Utah. The SuperSonics have won three straight.
The French rookie has started seven games, averaging 3.4 points and 4.1 rebounds in nearly 19 minutes per game.
Denver Nuggets: Forward Nene had surgery on his right knee.
Team physician Steve Traina repaired a torn anterior cruciate ligament, a torn medial collateral ligament and a lateral meniscus tear, the Nuggets said.
The Brazilian player was injured Nov. 1 in a season-opening loss to San Antonio after falling while the Spurs' Tim Duncan stole the ball from him. At the time, the Nuggets said he would likely miss the rest of the year.
Nene is in his fourth NBA season, all with Denver.