How the mighty have fallen.

The University of Pennsylvania and Princeton, who have combined to win the last 12 Ivy League men’s basketball titles, lost three of four games this weekend. The Quakers, Tigers and Elis are now locked in a three-way tie for first place in the Ivy League. Brown, winners of four straight Ivy games, sits only one game back.

Columbia (10-13, 5-5 Ivy) produced the biggest shocker of the weekend. The Lions became the first Ivy team to register a weekend sweep of Penn and Princeton since Dartmouth did it in March 1989.

On Saturday night in New York, Craig Austin led the Lions with 25 points as they sent Penn (9-15, 6-3) to a 69-57 defeat. Early in the second half, the Lions stormed to an 18-point lead and Penn never got closer than eight points the rest of the way. Columbia held the Quakers to under 30 percent shooting from the floor as Penn dropped its third game in its last five contests.

The previous night, the Lions defense began its wonderwork, holding Princeton (11-10, 6-3) to a season-low 27 percent from the floor in their 59-42 defeat of the Tigers.

Center Chris Wiedemann paced the Lions with 14 points on a perfect six for six from the floor. Columbia led 21-13 at halftime and would never relinquish the lead.

Princeton did not fare much better Saturday night at Cornell (7-16, 3-7), falling to the Big Red, 66-49. A Wallace Prather three-pointer capped a 9-0 Cornell run to open the second half, giving the Big Red a 38-23 lead with 15 minutes left in the game. The win snapped the Cornell’s 15-game losing streak against the Tigers.

Penn barely snuck by Cornell the previous night, 59-57. Geoff Owens threw down a game-winning alley-oop dunk from Dave Klatsky with three seconds left in the game, breaking a 57-57 tie. Penn shot a torrid 68 percent from the field in the second half, erasing a five-point Big Red halftime advantage. Ugonna Onyekwe led the Quaker attack with 15 points and Owens added a double-double with 11 points and 10 rebounds.

In Providence, R.I., Brown (11-11, 5-4) continued its quiet march up the Ivy League standings. The Bears beat Harvard (12-10, 5-5), 90-82 Friday night and dominated Dartmouth (7-16, 2-8), 86-67. It was the Bears’ second consecutive weekend sweep — the first time they have done that since the 1981-82 season. After losing four league games in a row, Brown has responded by winning its last four Ancient Eight contests.