CHAMPAIGN, Ill. - University of Illinois senior wrestler Chad Hay was named the Big Ten Wrestler of the Week after two wins in conference action this weekend. Twentieth-ranked Hay upset the fourth-ranked Kevin Black of Wisconsin on Friday en route to a 23-9 win over the No. 16 Badgers.    Hay's duel with Black was a see-saw affair, with Hay notching a  takedown at :28 in the third period. His victory helped the Illini down Wisconsin and stay in a tie for second in the Big Ten standings.    Hay, a Sandwich, Ill., native, improved his 133-pound record to 13-8  this season with a win over Brian Smiley of Indiana. He posted a 5-2  decision over the Hoosier as the 13th-ranked Illini beat IU, 29-9.  Hay is the first Illinois wrestler to earn conference honors this  season.    The Illini return to action on Sunday as they travel to Minneapolis,  Minn., to take on the No. 1 and unbeaten Minnesota Golden Gophers at  2 p.m.