The No. 1 seeds still have a chance at matching last year's history.
Connecticut, the top seed in the West, and Pittsburgh, No. 1 in the East, both won Thursday night, leaving open the possibility of the four top seeds reaching the Final Four for a second straight year.
Connecticut advanced with a 72-60 victory over Purdue, while Pittsburgh moved on with a 60-55 win over Xavier.
The regional finals are Saturday and Sunday.
STILL BIG EAST:@ The Big East had a record five schools in the round of 16, and halfway through Thursday's regional semifinal games, it still had five alive.
Connecticut beat Purdue 72-60 to advance to the round of eight, while Pittsburgh beat Xavier 60-55 to do the same.
Villanova, the other Big East team to play Thursday, faced Duke in a late game.
Louisville and Syracuse were to play their third-round games on Friday night.
CO-CENTERS:@ Connecticut's Hasheem Thabeet and Pittsburgh's DeJuan Blair were selected the co-players of the year this season in the Big East and their numbers were almost as close as the voting on Thursday.
The 7-foot-3 Thabeet had 15 points, 15 rebounds and four blocks in the Huskies' 72-60 victory over Purdue.
The 6-7 Blair had 10 points, 17 rebounds, two blocks and three steals in the Panthers' 60-55 win over Xavier.
BOARD WAR:@ Pittsburgh and Xavier entered their game Thursday night as two of the five best rebounding teams in the country and they played to a stalemate off the boards.
Pittsburgh came in with a 10.0 rebound margin over its opponents, second only to Michigan State's 10.1. The Musketeers were fifth with an 8.4 margin.
The Panthers won the game 60-55, but both teams had 44 rebounds with Pittsburgh getting 18 on the offensive end, one more than Xavier.
It certainly wasn't even at halftime as the Musketeers led 37-29 and were up 23-16 on the boards.
HUMBLING HUMMEL:@ Robbie Hummel carried Purdue in the first half against Connecticut, finishing with 15 points as the Boilermakers stayed within 30-25. The second half was a whole other story and it was written by the Huskies' defense.
Hummel, a 6-foot-8 sophomore forward, was 6-for-12 from the field in the first half, including 3-of-7 on 3-pointers.
In the second half he was 1-for-5 from the field and missed all three of his shots from behind the arc.
He didn't attempt a free throw in the game and finished with 17 points as the Boilermakers lost 72-60.
Source: AP News