Stanford freshman Reid Travis is out indefinitely with a stress fracture, the school announced.
Travis, a 6-foot-8 forward, underwent arthroscopic knee surgery in July but has started all 11 games for the Cardinal this season.
The team's leading rebounder, Travis helped lead Stanford to an upset win at No. 9 Texas last month by grabbing 14 boards. He also had 12 rebounds against Duke earlier this season.
Travis is averaging 7.5 points and 6.9 rebounds on the season.
In his absence, expect Rosco Allen and Michael Humphrey to see an increase in minutes. Allen is averaging 7.6 points and has started eight games, while Humphrey scored six points in 14 minutes against Arkansas-Pine Bluff in Stanford's last game.
Stanford (8-3) opens Pac-12 play on Friday against Washington State.