WACO, Texas (AP) -- Kansas had a share of its ninth Big 12 regular-season title in a row even before Ben McLemore scored a layup off the opening tip at Baylor.
That ended up being the only lead the fourth-ranked Jayhawks had, and as close as they came to claiming the outright league title on the final day of the regular season.
Pierre Jackson had 28 points with 10 assists and Cory Jefferson scored 25 points, mixing in his first three career 3-pointers with his usual powerful dunks, and Baylor handed the Jayhawks their worst loss in seven years. The 81-58 loss Saturday night kept Kansas from winning conference regular-season title outright for the fifth year in a row.
''It doesn't feel like we've won it at all. We tied Kansas State,'' said Jeff Withey, one of four Kansas seniors in the starting lineup with standout freshman McLemore. ''It's cool to win, obviously. To win nine in a row is huge. But it just stinks to lose.''
Especially like this, after winning their last seven games.
The Jayhawks (26-5, 14-4 Big 12) will still be the No. 1 seed for next week's conference tournament in Kansas City.
''Yeah, I'm happy we got a ninth, I'm never going to apologize for winning a league championship,'' Kansas coach Bill Self said. ''It's not exactly the way we scripted it, which I think is pretty obvious. They were so much better than us. ... I'm not happy, but I'm a lot happier than I would be if it was different and we finished second.''
The Jayhawks knew they already had a piece of the Big 12 title after ninth-ranked Kansas State (25-6, 14-4) lost 76-70 earlier Saturday at No. 13 Oklahoma State. But the KU loss gave the rival Wildcats a share of their first regular-season conference title since 1977 in the Big Eight.
''I'll be candid with you: I was excited and knew that we got piece,'' Self said. ''I thought we would play better because we knew we did. Because there would be no pressure, total freedom, confidence going out and it didn't work out that way for us. We got off to a rough start.''
McLemore's quick basket gave the Jayhawks no momentum.
Baylor (18-13, 9-9) scored the next six points, including a two-handed slam dunk by Jefferson, and led the rest of the game.
Jefferson had a pair of early dunks before hitting the first 3-pointer of his career for a 22-13 lead. The 6-foot-9 forward was 0 for 7 from long range before that.
''It's something I've been doing in practice, and I just figured I might as well do it in a game,'' Jefferson said.
Jackson, the Big 12's leading scorer, and Jefferson both made 11 of 13 field goals - Jefferson made all three of his 3-pointers. A.J. Walton added 12 points for Baylor and Isaiah Austin had 11 for Baylor.
McLemore had 23 points for Kansas, which hadn't lost this big since a 25-point loss to Texas in February 2006.
Kansas used an 11-0 run in the second half to get within 61-55 with 6:23 left after consecutive baskets by Perry Ellis, who finished with 12 points.
''When we cut it to six, I still thought we were climbing a pretty steep hill,'' Self said. ''They were terrific and we weren't good. They were terrific and had a lot to do with us not being very good. And, of course, two players played about as well as any two players against us in a long, long time off the same team.''
After the Jayhawks' spurt, Jackson stole a ball from McLemore and drove for a layup made between two defenders. After Ellis missed a shot, Jackson got the ball and made a pass ahead to Brady Heslip for an easy layup.
The Bears kept piling on after that, and because of that could still have a shot at an at-large NCAA berth with a couple of wins at the Big 12 tournament.
''We were just focused. We knew what was at stake, we know how big this game was,'' Jackson said. ''We handled business.''
Baylor had lost six of its previous seven games and was already locked in as the No. 6 seed in the Big 12 tournament. The Bears play Oklahoma State on Thursday night in Kansas City - they split their two regular-season matchups.
Kansas, which has won an NCAA-best 56 overall conference regular-season titles, plays Thursday against the West Virginia-Texas Tech winner.
Jefferson had 18 points by halftime, including a 3-pointer for the last points of the half. That came on the possession right after he took a charging foul that wiped out a basket by Elijah Johnson.
''Cory was O-for for his career and now I think we'll have to design some plays for him to get him 3-point shots,'' Baylor coach Scott Drew said. ''Cory makes 3s in practice and works on them. ... If you don't go out and guard him, Cory is going to shoot the 3 and he was on fire.''