San Diego Chargers running back Ryan Mathews believes he'll be in the backfield for his team's Sept. 10 opener against the Oakland Raiders, despite the broken clavicle he suffered on his first carry of the preseason Thursday night.

Mathews underwent surgery Friday and the prognosis for his return was set by the team at four to six weeks.

The running back spoke Sunday for the first time about the injury and sounded confident he'll be back by the time the season starts. He said that his doctor told him that he could be back in as few as three weeks.

"I think I heal pretty fast," Mathews told reporters, according to U-T San Diego. "I think I'll be good in time to play against the Raiders. ... I'm happy it happened now than against the Raiders. It's better that it happened now, just to get it out of the way. It gives me a few weeks to recover and get back at it."

Coach Norv Turner said it'll take a "fortunate" recovery for Mathews to play in four weeks.

Mathews led the Chargers with 1,091 yards rushing and averaged 4.9 yards per carry last season, earning him a trip to the Pro Bowl.

Entering training camp last month, Turner said Mathews was in the best shape of his career and should pile up bigger carrying and scoring numbers this year because he'd get additional snaps near the goal line.

"You work hard and then something like that happens," Mathews said, "but I figure that I'm getting them all out of the way now, and then I'll have the whole season, a long season, to look forward to."

Mathews said he considered the injury a freak mishap. He said he "landed wrong" and then Green Bay linebacker A.J. Hawk landed on him.

"It's just something that happens," Mathews said. "You've just got to walk away from it, kind of laugh at it and get better."

Turner has said several backs, including Ronnie Brown, Jackie Battle, Le'Ron McClain and Curtis Brinkley, will play in the three remaining preseason games.

Information from The Associated Press was used in this report.