Bye weeks present USC with an opportunity to get healthy, and this one is coming at just the right time.Four key USC players sat out of practice with a multitude of injuries, but the Trojans did get some good news about one of their playmakers.Giving it the boot · Damian Williams is out of the protective boot and could start running Monday. – Mike Lee | Daily TrojanRedshirt junior wide receiver Damian Williams remained in sweatpants and did not practice, but he was not wearing a boot on his injured ankle like he was on Tuesday.Coach Pete Carroll said Williams expects to run on Monday, and he will be evaluated from there.“He’s encouraged,” Carroll said of the team’s leader in receptions, receiving yards and receiving touchdowns.Running backs redshirt junior Allen Bradford and junior Joe McKnight also missed practice.Bradford is recovering from a bone bruise in his foot, while Carroll said McKnight was suffering from blurred vision due to migraines.uWith Williams out, other receivers have had to step up, including junior Ronald Johnson and redshirt freshman Brice Butler.“We got a lot of guys stepping in, making big plays,” Johnson said. “We’re not really missing a beat, but at the same time, he’s a big key player, we’d love to have him back.”The duo caught 13 of freshman quarterback Matt Barkley’s 21 completions on Saturday against Stanford. Johnson had seven grabs for 69 yards, while Butler hauled in six grabs for 96 yards and a score.Johnson has been impressed with Butler’s play.“He’s really coming up,” the junior said. “He’s learning the game and making plays.”Johnson continued to impress in his own right during practice, streaking down the left sideline and beating freshman defensive back Byron Moore on a 50-plus-yard touchdown pass from Barkley.He said he doesn’t feel any added pressure without Williams in the lineup.“It’s an opportunity,” Johnson said.uThe open week also gives a number of younger Trojans a chance to get more repetitions in, and a handful of players are taking advantage of that opportunity.One of those players is Moore.“We learned some stuff that he hadn’t grasped yet,” Carroll said. “Now we can help him progress.”Another is freshman offensive tackle Kevin Graf.“I can’t tell you that he’s set the world on fire yet but he has to battle with the first group when he’s in there,” Carroll said.Graf’s father, Allan Graf, played three years for USC in the early 1970s, including with the Trojans’ 1972 national championship team. His brother, Derek, lettered in 2002.Sophomore linebacker Uona Kaveinga also impressed coaches, making a number of stops in 11-on-11 drills.