BLAINE, Minn. (AP) PGA Tour rookie Jackson Koivun shot a 61 in the third round of the 3M Open on Saturday to take a three-stroke lead at 20-under par, setting a tournament record with a 28 on the back nine at the TPC Twin Cities.Emiliano Grillo and Ben Kohles each had a 65 and are tied for second at 17 under. Michael Brennan shot a 63 and shared fourth with Chandler Phillips at 16 under. Denny McCarthy, Billy Horschel and Michael Kim were in sixth at 15 under.Scottie Scheffler, the world's top-ranked player, was six strokes behind Koivun in a four-way tie for ninth place with Davis Thompson, Seamus Power and Brian Harman.The 21-year-old Koivun, who was the top-ranked amateur player after a standout college career at Auburn and turned pro last month following the U.S. Open, had two eagles and six birdies to separate from the pack on a steamy and still afternoon that was ideal for low scores.Koivun sank a 12-foot putt on the 12th green and an 14-footer on the 18th to eagle two of the three par-5s on the lake-filled course, which joined the tour schedule in 2019. Koivun, who tied for 10th two weeks ago at the ISCO Championship in Kentucky, shot a 64 on Thursday and a 68 on Friday.___AP golf: https://apnews.com/hub/golf