The top-ranked Minnesota Gophers, who rolled to the championship at the National Duals last weekend in Columbus, Ohio, begin a tough stretch of Big Ten meets this week.    Minnesota will travel to No. 6 Michigan on Friday before wrestling at No. 13 Michigan State on Sunday.    The Gophers then will face No. 3 Iowa in a much-anticipated matchup on Feb. 1 at the Target Center in Minneapolis. More than 8,000 tickets have already been sold for the meet between the two Big Ten powers.    Minnesota won the NCAA title last season, halting a string of six consecutive championships won by the Hawkeyes.    Another big meet this weekend will involve No. 2 Ohio State, a team that knocked off Oklahoma State and Oklahoma to reach the finals of the National Duals. The Buckeyes will battle Iowa.    Iowa, third at the National Duals, will return to Columbus to face the red-hot Buckeyes at St. John Arena. The Hawkeyes will then meet Northwestern on Sunday at home.    Iowa State, ranked fourth, will return home for a dual meet with North Carolina State on Friday night at Hilton Coliseum.    ISU senior Cael Sanderson, who pinned five opponents and won another match by default at the National Duals, is now 144-0 in his career. Sanderson, a three-time NCAA champion at 184 pounds, is 25-0 at 197 this season.    Sanderson is scheduled to face No. 2 Jon Trenge of Lehigh in Monday's NWCA All-Star meet at Hofstra. Sanderson beat Trenge 16-5 earlier this season. It was Sanderson's closest bout of the season.    Oklahoma State, ranked fifth, will wrestle at No. 9 Missouri in a key Big 12 dual on Friday. Missouri is undefeated in duals.    Oklahoma, ranked seventh, is off until facing No. 15 Northern Iowa on Feb. 1 in Norman.