Louisville will be without a key player when it returns following a week off to host Bowling Green on Saturday afternoon.The Cardinals (2-0) will be without linebacker Stanquan Clark, one of three returning starters on defense.Clark underwent surgery on his lower leg and might miss the rest of the season, coach Jeff Brohm said Monday. Clark was injured in Louisville’s 28-14 win over James Madison on Sept. 5.Defense has been a strength for Brohm’s team so far this season. The Cardinals are averaging five sacks a game and rank eighth nationally in yards allowed at 206.5 per contest.Brohm credited the defense on working to limit opponents from getting chunk plays of 20 or more yards. That was a priority for the team in the offseason, especially in defending deep passes.”Yes, there will be situations where we’re going to be aggressive and take a few chances, but in the end, in certain coverages, we were getting beat when we really weren’t being aggressive last year,” Brohm said.On Saturday, that unit will face an offense led by former Notre Dame quarterback Drew Pyne. The sixth-year player leads the Mid-American Conference in completion percentage at 67.1.The Falcons (2-1) have been outgained in both of their games against FBS competition. Cincinnati recorded 333 of its 441 yards in the air, while Liberty gained 152 of its 346 on the ground.Louisville has big-play capabilities among its receiving corps and running backs.