PITTSBURGH -- Notre Dame coach Mike Brey guided the Irish to a thrilling, 67-64 overtime win over Butler in the NCAA tournament hours after losing his mother to a heart attack at age 84.

Betty Brey, an Olympic swimmer and one of Brey's biggest influences, passed away early Saturday in Florida. Brey admitted it still hadn't registered, but he felt the presence of the person he called an "unbelievable woman, a woman ahead of her time and probably the real driving force behind everything I've done," as the final seconds ticked down.

Jerian Grant scored 16 points for Notre Dame (31-5), which moved on to the Sweet 16 for the first time since 2003. The Irish will play Kansas or Wichita State on Thursday in the Midwest Regional semifinals in Cleveland. With ND's win, the ACC moved to 9-0 in this season's tournament, with three more teams playing Sunday. According to ESPN Stats & Information, the most wins any conference has had through the round of 32 is 11, by the Big East in 2009.

Steve Vasturia led Notre Dame with 20 points. Demetrius Jackson added 13 points, and Zach Auguste had seven points and 13 rebounds for the Irish, who beat the Bulldogs for the first time in 26 years.

The ACC tournament champions are used to tight games. They didn't blink when Butler did what Butler always does this time of year: rally from an early deficit to push a higher-seeded opponent to the brink.

But not over it.

"We had the game where we wanted it,'' Butler coach Chris Holtmann said. "We just weren't able to make enough plays there late."

Roosevelt Jones played through an injured left knee while scoring 23 points for Butler (23-11), but the Bulldogs never led in the extra session, after they missed on two chances to win in regulation. Notre Dame senior guard Pat Connaughton slammed Kellen Dunham's shot from the corner into the ground, and senior center Kameron Woods couldn't convert an out-of-bounds alley-oop at the buzzer.

Connaughton shouted "not tonight" after his block. He was right.

Connaughton snapped a 59-all tie with a 3-pointer from the right corner. Dunham got the Bulldogs within a point with two free throws, but the Irish drilled their sixth -- and last -- 3-pointer of the game when Vasturia knocked a shot down from the same spot as Connaughton.

Grant, a senior who missed most of the 2013-14 season due to an academic issue, then split the defense and laid it in with the shot clock nearing zero.

"We made big plays down the stretch. We've been doing that all year," Grant said. "We're playing with a lot of confidence right now. We want to keep it rolling."

ACC's Incredible Tournament The ACC is 9-0 with three more teams playing Sunday. The most wins any conference has had through the round of 32 is 11 by the Big East in 2009. If Duke, Virginia and Louisville all win on Sunday, the ACC will have a record six schools in the Sweet 16. The most schools any conference has put in a Sweet 16 is five by the Big East in 2009. Most Wins Through Round Of 32

Conference In Single Season Year Conference W-L 2009 Big East 11-2 2013 Big East 10-5 2012 Big East 10-5 2008 Big East 10-5 >>ACC: 9-0 entering Sunday -- ESPN Stats & Information

The two schools separated by 147 miles of Indiana highway met regularly from 1908-95 but had played just once in the past 20 years, a Bulldogs win in the 2006 preseason NIT.

The balance of power between the programs has shifted mightily in two decades. The Bulldogs are a March fixture with a pair of memorable national title game appearances since 2010 alone. The Irish have been modestly successful under Brey but have struggled to translate regular-season wins into lengthy tournament stays.

The Irish promised this spring would be different. They shot their way to an improbable ACC tournament title and beat Duke and North Carolina behind an efficient offense and ability to limit mistakes.

It's a formula that has worked for Butler during its rise from mid-major marvel to newly minted citizen of the rejiggered Big East. The Bulldogs overcame the abrupt departure of coach Brandon Miller in October with gritty, grind-it-out defense and a relentless commitment to rebounding.

Notre Dame led by as much as 10 in the first half, but the Bulldogs -- as they tend to do this time of year -- would not go away. Wearing reams of tape, compression pants and an unwieldy brace, Jones kept finding open space to get Butler back in the game.

TIP-INS

Butler: Jones said he would have to be "tackled" to be kept out of the game. He made nine of 19 shots while playing 44 of the game's 45 minutes. ... Senior guard Alex Barlow shot just 1-of-6 and missed all four of his 3-point attempts before fouling out early in overtime.

Notre Dame: Connaughton played in his school-record 137th game, which broke the record he shared with former point guard Tory Jackson. ... Jackson made four of eight shots two days after being raked across the eyes late in the round of 64 win over Northeastern and complaining of blurred vision afterward.

UP NEXT:

Butler loses seniors Woods and Barlow but returns Dunham and Jones.

Notre Dame will try to reach the regional final for the first time since 1979.

The Associated Press contributed to this report.