As the Trojans gear up to hit the road to take on the Colorado Buffaloes on Friday night, they will be playing in a climate very different from that of their home base.The frigid temperatures in Boulder are a far cry from the sunny, warm days in Los Angeles, but interim head coach Clay Helton does not consider that an excuse for poor performance from his players.“We’ve always taken the approach of we don’t make excuses, whatever the factors are out there,” Helton said. “They pay us to find the answers, not make excuses.”The high in Boulder on Friday is projected to be 53 degrees, but temperatures are expected to fall below freezing by gametime. The plan, especially in the high altitude, is to substitute more frequently.“It should be a really nice night for football, especially with no precipitation,” Helton said. “With the altitude, you’ve always got to get used to it to go up there, but [Colorado’s] got to play in it, too. We’ve got plenty of depth right now that I think we can roll guys in. If it turns into a 100-play offensive game for them, we’re going to have to roll a lot of guys. Hopefully that doesn’t happen.”USC has played in near-freezing temperatures this season already when the team lost to Notre Dame, 41-31, in South Bend back on Oct. 17.Helton described redshirt senior quarterback Cody Kessler’s clever strategy to get acclimated to the weather, something that Matt Barkley also did during his time under center at USC.“They’ve got the bag of ice out there, freezing their hand up and throwing with their hand being cold all week,” Helton said. “That’s kind of a ritual around here.”USC is 4-0 all-time at Colorado and 9-0 overall. The last time the Trojans played in Boulder was in 2013, when Kessler completed 19-of-28 passes and threw for 184 yards and two touchdowns in 29-degree weather.“We really feel like we operated effectively the last time we were there,” Helton said. “We’re not going to use [the weather] as an excuse.”At practice on Wednesday, the Trojans focused on defending the red zone in what is expected to be a high-scoring affair.“We focused on our red zone, which is going to be critical against a very good offense,” Helton said. “The bend but don’t break defense and, offensively, scoring touchdowns instead of field goals.”On the injury front, redshirt senior running back Tre Madden will not play, sidelined with a bone bruise in his knee. Madden has been playing through an injury and saw limited action in USC’s win last week against Arizona. His absence will place a heavier load on USC’s other featured tailbacks, freshman Ronald Jones II and junior Justin Davis.“[Madden’s] knee right now is still hurting,” Helton said. “We decided we’re going to rest him this week and reevaluate next week. It may be a couple week thing. We’ll have to see. At this point in time, we want to get him 100 percent healthy.”Madden will travel with the team, however, with Helton hoping to utilize the senior as a leader and a mentor.“He’s too good of a leader,” Helton said. “He keeps me sane. There’s no way he won’t sit right beside me on the plane. He’ll be assistant head coach this week.”Redshirt senior defensive end Claude Pelon, who has a knee injury, and redshirt sophomore center Khaliel Rodgers, who has a shoulder injury, are expected to play. According to Helton, Pelon will be limited to 15-30 snaps on Friday.Helton also revealed that freshman linebacker John Houston Jr., an All-American last season for Junipero Serra High School, is undergoing rehab for a back injury that carried over from high school. Houston Jr., a four-star recruit, was the top-ranked inside linebacker by ESPN coming out of high school.