San Diego Chargers running back Ryan Mathews participated in practice on Monday, which represented his first work with the team since breaking his clavicle on Aug. 9.

However, Mathews has not yet been cleared for contact, according to the San Diego Union-Tribune, which makes it doubtful he will be ready to play in the regular-season opener against the Oakland Raiders next Monday night.

Mathews was injured on his first carry of the preseason, and typical recovery time for a broken clavicle is four to six weeks. But he has said frequently he would return sooner than expected. Last week, he suggested he'd be ready to play in the season-opener.

Mathews participated in individual drills Monday, but he may not be far enough along to play in the opener.

Mathews rushed for 1,091 yards last season while playing in 14 games, including 13 starts.

If Mathews is out, veteran Ronnie Brown will start.