HOUSTON — Portland Trail Blazers center Greg Oden will miss at least two more games because of a bone chip in his left knee.

Oden was hurt in a collision during a game at Golden State before the All-Star break. The 7-foot Oden missed the rookie challenge and will miss sit out Tuesday's game in Houston and Wednesday's game in San Antonio.

Coach Nate McMillan said there was a "slight chance" Oden would participate in practice on Thursday. McMillan said he wanted to see Oden run before determining when Oden would play again.

"We thought, everybody thought, he would be able to be moving by now," McMillan said. "Things just keep getting bumped back."

McMillan said doctors have assured him that the injury won't turn into a long-term absence. But McMillan admitted he's starting to get worried.

"We are into the part of the season where we need our bigs," McMillan said.

Oden, the top pick in the 2007 draft, sat out last season after microfracture surgery on his right knee. He missed six games early this season with a foot injury.

The 7-foot Oden has averaged nine points and just over seven rebounds in 39 games this season. Joel Przybilla started for Oden on Tuesday.