DEERFIELD, Ill. -- The only break Tyrus Thomas can catch these days is a bad one.
The Bulls forward, who hurt himself earlier this morning during a weightlifting session at practice, fractured the radius bone in his left forearm. X-rays confirmed the injury Friday afternoon. He will have surgery Saturday morning, according to the Bulls. Thomas is expected to miss four to six weeks.
In four games this season, the fourth-year player from LSU is averaging eight points and five rebounds in 21 minutes.
Thomas sat out Tuesday night's game with the flu and did not play in the fourth quarter in last Sunday's loss against the Heat. Rookie Taj Gibson was scheduled to start in Saturday's game against the Bobcats and is expected to get the bulk of Thomas' playing time.
The 6-foot-10 Thomas was the fourth overall pick by Portland in the 2006 draft and then had his draft rights traded by the Trailblazers, along with Viktor Khryapa, to the Bulls for the draft rights to LaMarcus Aldridge.
Thomas started to emerge as a player last season when he averaged 10.8 points, 6.4 rebounds and nearly two blocks a game. He made 61 starts and appeared in 79 games for the Bulls.
"He tweaked his arm a little bit and he's pretty sore," Bulls coach Vinny Del Negro said before the results of the X-rays were revealed.
Nick Friedell covers the Chicago Bulls for ESPNChicago.com. The Associated Press contributed to this report.