JEFF SCHORFHEIDE/Herald file photoIn 2006, the Wisconsin football team boasted one of thestingiest defenses in the Big Ten. But after struggling much of last season, itlooks to get back on track this year, starting with the guys in themiddle. Jonathan Casillas, a preseason first team all-Big Tenselection, is one of the most experienced members of the senior-dominatedteam. Expected to shine in his final season with the team, Casillasinjured his knee just two weeks before the end of fall camp, putting his careerat Wisconsin in jeopardy.“I thought my career was over, at least I’d have to sitout for this year,” Casillas said. “I was thinking the worst.”Fortunately for Casillas, the knee injury would onlysideline him for the remainder of camp and the first two games of the season.Despite having one of its main playmakers absent for the first pair of games,the defense knew that other players would be able to step up in hisabsence. In addition to starters Jaevery McFadden and DeAndre Levy, BlakeSorensen — a sophomore from Eden Prairie, Minn. — was called upon to step infor Casillas. Although he had never started a game on defense for theBadgers before the 2008 season, Sorensen excelled in his opportunity atlinebacker. In the opener against Akron, Sorensen recorded four tackles,including a five-yard stop behind the line of scrimmage, as the UW defense heldthe Zips to just 70 yards on the ground. The following week againstMarshall, Sorensen recorded three more tackles, paving the way for a Badgerdefense that held Darius Marshall and the Thundering Herd again to just 70rushing yards.Although Casillas was forced to remain on the sidelines, he was still able tohelp Sorensen out verbally. Noticing some of the minor errors thatSorensen was making on the field, Casillas was able to give the underclassman afew pointers on how to correct his mistakes.The advice that Casillas gave paid big dividends for theteam.“Sorensen plays a lot for us, and I think he did agreat job behind me,” Casillas said. “I think if I’m not ready to gothis Saturday, which most likely I will be able to, I think he’s ready to goagain.”In addition to proving himself as a reliable backup to Casillas, Sorensen alsomade quite an impression on the coaching staff.“Blake did a great job in his place and we’re excitedabout him,” defensive coordinator and linebackers coach Dave Doeren said.Sorensen’s success in the first two games can’t be solely attributed to him orCasillas. According to Casillas, both McFadden — the leading tackler on theteam thus far — and Levy also gave Sorensen some useful advice. With hisperformances, Sorensen has seemed to put away any doubt about the future of thelinebacking core. “He’s still young, but I think he put it in coachDoeren’s mind that — hopefully nothing will happen to me, but if something does— they can count on him again, and next year they got nothing to worryabout,” Casillas said.Even before Sorensen steps onto the field on Saturday at Fresno State, Casillasalready has some advice for his teammate.“Make [Fresno] our home,” Casillas said of thetheme for his next speech. “We play good at home, so why don’t we just addthat to our edge?”In addition to the bond that the defense shares, its successcan also be attributed to the way they play together as a unit.“We’ve been playing together for years,” Casillassaid. “We have so much chemistry. I make sure I tell the D-line every dayI love them. They’re my brothers, and I’m ready to fight for them any time anyday, any Saturday.”According to Sorensen, Casillas’ knowledge and vocal leadership is part of whatis preparing him to be a leader next year.“I’ve learned a lot from him,” Sorensen said ofhis fellow linebacker.With Casillas leaving next year, the tips and lessons thathe leaves with Sorensen can only benefit him. Sorensen said he will be glad toembrace a leadership role next year, and with himself, Elijah Hodge andMcFadden all returning next year, the defense may again continue to be a forceto be reckoned with.