While No. 7 Purdue finds itself just below the Big Ten Conference’s top spot, 16th-ranked Wisconsin is seeking an opportunity to challenge for the league title.The two collide on Saturday when the Badgers visit the Boilermakers in West Lafayette, Ind., for a matchup that could help determine seeding for next month’s conference tournament as well as the NCAA Tournament.The Boilermakers (19-6, 11-3 Big Ten) fell out of first place Tuesday night with a 75-73 loss at new leader Michigan, while Wisconsin (19-5, 9-4) owns sole possession of fourth after its 74-63 victory at Iowa on Feb. 8.Badgers forward John Blackwell had a simple explanation for why the Badgers held the high-scoring Hawkeyes 22 points under their per-game average.”We just shut their water off,” he said.While Wisconsin turned the spigots off on one end, it poured John Tonje at the Iowa defense on the other end. Tonje scored seven straight points to start a game-ending 16-4 run and finished with a game-high 22 points, going 9 of 10 at the line.A graduate student who played just eight games last season at Missouri before suffering a season-ending injury, Tonje is enjoying the best season of his career, averaging 18.6 points per game and converting 46.8 percent of his shots from the field.”He picked his spots,” Badgers coach Greg Gard said of Tonje’s late outburst. “He was able to attack when the floor was a little more spread and we had a little more balance. We had gotten the defense distorted.”Blackwell (15.3 ppg), Max Klesmit (10.1) and Nolan Winter (10.0) also average double figures for Wisconsin, which is averaging 81 ppg, the most in Gard’s 10-year tenure. It also leads Division I in foul shooting at 84.1 percent.Given that number, the Boilermakers would be well advised to play a cleaner brand of defense than they did Tuesday night. Purdue outscored Michigan by 10 points from the field but made just eight trips to the foul line, while it committed 23 fouls and gave the Wolverines 26 attempts at the stripe, getting outscored by 12 points there.