LOS ANGELES — USC receiver Ronald Johnson will be out six to eight weeks after breaking his collarbone during the No. 4 Trojans' mock game.

Johnson was the Trojans' third-leading receiver last season with 33 catches for 570 yards and eight touchdowns. The junior was expected to start for USC this season alongside Damian Williams.

Johnson was hurt Saturday during the second series of the mock game at the Coliseum when he was tackled after catching an underthrown 34-yard pass from freshman quarterback Matt Barkley.

Coach Pete Carroll says the injury is "just a crusher."

Williams, the Trojans' leading receiver last season, will take Johnson's spot on the offense, and junior David Ausberry will move into the starting lineup.