San Diego Chargers starting running back Ryan Mathews suffered a broken clavicle in the opening quarter of his team's first preseason game against the Green Bay Packers.
Mathews was hurt on his only carry of the contest, a five-yard run. He will have surgery Friday and is expected to miss 4-to-6 weeks.
The third-year Fresno State product rushed for 1,091 yards and six touchdowns a year ago.
San Diego defeated Green Bay, 21-13.