PORTLAND, Ore. — Portland Trail Blazers center Greg Oden will miss two to four weeks because of an injury to his right foot.

The team said Wednesday that MRI and computerized axial tomography scans confirmed Oden has a mid-lateral foot sprain.

Oden, who missed all of last season after knee surgery, injured his foot in the first quarter of the Blazers' 96-76 season-opening loss to the Los Angeles Lakers on Tuesday night.

"I was trying to go get a rebound, and kind of came down on Derek Fisher's foot on like the third play of the game. I kind of fell and didn't think twice about it," he said after the game.

Oden missed four field goals and two free throws in 13 minutes of play.

The 7-foot center was the top pick in the 2007 draft. But even before his rookie season started, it was postponed by microfracture surgery on his right knee.

Trail Blazers coach Nate McMillan had not yet heard of the MRI results when he addressed reporters Wednesday at the team's practice facility in Tualatin, Ore.

"You don't want injuries, and he's worked so hard throughout this summer to get himself back," McMillan said. "And we tried to do everything we could to get him ready for the season and the opener, and he steps on a guy's foot."

Blazers guard Brandon Roy, who also spoke before the tests were complete, said the team will prepare to move forward without Oden for Friday night's home opener against San Antonio.

"I feel bad for him," Roy said. "I know this is a big year for him and he had a lot on his shoulders."

Oden's first game was highly anticipated by Blazers fans, who had waited a long time to see the top draft pick. The team had not had a No. 1 pick since 1978, when they chose center Mychal Thompson of Minnesota.

After he was held out last season, Oden rolled his ankle in the first practice of the fall. That injury wasn't serious, however.

At Ohio State, Oden averaged 15.7 points and 9.6 rebounds, but Oden struggled with a wrist injury. He led the Buckeyes to the national championship game, scoring 25 points and grabbing 12 rebounds in the loss to Florida.