CHAMPAIGN, IL - Defending Big Ten Champions Minnesota are holding onto a slim 1-point lead heading into the semifinal and consolation wrestleback session tonight at 7 p.m.    The top-ranked Gophers scored 71 team points and currently stand 1 point ahead of Iowa with 70, while second-ranked Michigan stand five points behind Ohio State with 52 points.    Several seeded wrestlers fell in quarterfinal action. Two Hawkeye upsets helped lift the third-ranked Hawks to second in the team standings. Seventh-seeded Luke Eustice of Iowa pulled a major quarterfinal upset over second-seeded Chris Fleeger of Purdue, winning 2-1, while #6 seed Luke Moffitt won a sound 9-2 decision over third-seeded Grant Hoerr of Wisconsin.    Host Illinois felt the sweet victory and the agnony of defeat with a couple upsets. Sixth-seeded Chad Hay of Illinois handed third-seeded Foley Dowd of Michigan a 4-1 loss, while sixth-seeded Gray Maynard of Michigan State scored an overtime fall over third-seeded Griff Powell of Illinois. The Gophers maintain their team lead despite third-seeded Jacob Volkmann's giving up an overtime pin to sixth-seeded Brady Reinke of Wisconsin.    Team Scores after first session:  1. Minnesota, 71; 2. Iowa, 70; 3. Ohio State, 57; 4. Michigan, 52; 5. Illinois, 44; 6. Penn State, 29; 7. Indiana, 21; 8. Michigan State, 19; 8. Purdue, 19; 10. Wisconsin, 18; 11. Northwestern, 4    The semifinal and consolation wrestlebacks are set for 7 p.m. CT tonight. The Semifinal matchups are as follows:      Semifinal Matchups  125 Pounds  #1 Leroy Vega of Minnesota vs. #5 Twan Pham of Illinois   #3 AJ Grant of Michigan vs. #7 Luke Eustice of Iowa    133 Pounds  #1 Ryan Lewis of Minnesota vs. #4 Cliff Moore Iowa  #6 Chad Hay Illinois vs. #7 Jeff Ratliff Ohio State    141 Pounds  #1 Scott Moore Penn State vs. #4 Chad Erickson Minnesota  #6 Luke Moffitt Iowa vs. #2 Robert Sessley Ohio State    149 Pounds  #1 Mike Zadick Iowa vs. #4 Keaton Anderson  #3 Mike Kulczycki Michigan vs. #2 Jared Lawrence Minnesota    157 Pounds  #1 Luke Becker Minnesota vs. #5 Matt Anderson Iowa  #6 Gray Maynard Michican vs. #2 Ryan Bertin Michigan    165 Pounds  #1 Matt Lackey Illinois vs. #5 Oscar Santiago Purdue  #3 Doc Vecchio Penn State vs. #2 John Clark Ohio State    174 Pounds  #1 Otto Olson Michigan vs. #4 Ryan Lange Purdue  #6 Brady Reinke Wisconsin vs. #2 Tyler Nixt Iowa    184 Pounds  #1 Andy Hrovat Michigan vs. #4 Jessman Smith Iowa  #3 Damion Hahn Minnesota vs. #2 Viktor Sveda Indiana    197 Pounds  #1 Nick Preston Ohio State vs. #4 Pat DeGain Indiana  #3 Kyle Smith Michigan vs. #2 Owen Elzen Minnesota    285 Pounds  #1 Steve Mocco Iowa vs. #5 John Lockhart Illinois  #3 Garrett Lowney Minnesota vs. #2 Tommy Rowlands Ohio State