The freshman phenom had 33 points and 17 rebounds, Grayson Allen made his first five 3-pointers and Duke rolled to an 88-70 victory in the tournament quarterfinals Thursday night.
"Bagley was just ... the first pick in the draft," Notre Dame coach Mike Brey said. "He's a can't-miss star."
Allen finished with 23 points and the second-seeded Blue Devils (26-6) advanced to play archrival North Carolina in the second semifinal Friday night. The 12th-ranked and sixth-seeded Tar Heels eliminated No. 3 seed Miami, 82-65.
Duke, the defending champion after beating Notre Dame in the title game last year, earned its 100th ACC Tournament victory.
"We're on a roll," Bagley said. "I definitely think we're getting better."
Bonzie Colson had 18 points and nine rebounds for the 10th-seeded Fighting Irish (20-14), unable to score the marquee victory over a top team that would have been a huge boost to their NCAA Tournament resume.
Injuries to Colson and senior guard Matt Farrell derailed Notre Dame in the middle of the season, and now the Irish have to hope the selection committee focuses on how good they can be when healthy.
"I'm definitely going to go to church on Sunday morning," Farrell said.
The undersized Fighting Irish had no answer for Bagley's athleticism and rare leaping ability in the lane at 6-foot-11. The ACC Player of the Year shot 15 for 23 and came within one point of his career high set against Texas in late November. It was his fourth game with at least 30 points and 15 rebounds.
"He's one of the toughest players I've ever gone against. He's really explosive," Colson said. "He deserved all the honors he got this year."
Trevon Duval dished out 11 assists for the Blue Devils, who overcame foul trouble for big man Wendell Carter Jr. that limited him to four points in 17 minutes.
Duke coach Mike Krzyzewski said Carter has a foot injury that kept him out of practice this week.
"He played gingerly tonight, and we'll see about tomorrow," Krzyzewski said.
When the Irish lost 88-66 at Duke in late January during a seven-game skid, Colson and Farrell were both out. So they had good reason to believe this matchup could be much different.
The game began at a blistering pace, with both teams zooming up and down the court. They combined to go 8 for 13 on 3-pointers and Duke already had a 25-17 lead before the first timeout 7:18 in. Allen was 4 for 4 from outside the arc at that point, hitting three straight 3s before Brey called a timeout.
With the Irish playing their third game in three days, this one against a rested Duke squad that had been off since beating rival North Carolina on Saturday night, the fast start seemed to favor the Blue Devils as they built a 13-point advantage midway through the first half.
"We started pushing the ball early and got some good looks," Allen said.
But the Irish trimmed it to 41-37 at halftime - despite Allen's 17 points - and quickly got within two 40 seconds into the second.
That's when Duke took control as Bagley and Duval combined for 10 points in a 12-2 spurt that gave the Blue Devils a 53-41 cushion.
Duke extended it to 80-62 with 4:30 remaining, and there would be no big rally for the Fighting Irish this time. Notre Dame won its first two games in the tournament, erasing a 21-point deficit in the second half Wednesday night against Virginia Tech for the biggest comeback in school history.
Notre Dame: Hard to know how the committee will evaluate a team that went 14-5 with Colson and 6-9 without him. Farrell also missed several games during Colson's absence with an injured ankle. Brey said Wednesday he has a top-20 team with his stars healthy and it deserves a spot in the field of 68.
"I hope they get in. I think they can beat anybody," Krzyzewski said. "Mike has that team together all year, forget it."
Notre Dame opened 13-3 and was ranked No. 5 in the country in late November after beating then-No. 6 Wichita State to win the Maui Invitational. Now, the Irish must hope they did enough with Colson and Farrell in the lineup to impress the committee. If not, Notre Dame could be a favorite to win the NIT.
"Our guys emptied the tank," Brey said. "No matter what happens, we'll be accepting and proud."
Duke: With a chance to earn a No. 1 seed in the NCAAs, the Blue Devils are looking for their second consecutive ACC Tournament championship. They already have a record 20. ... Duke improved to 100-44 in the ACC Tournament, including 62-22 with 14 championships in 38 appearances under Coach K. ... Since switching primarily to a 2-3 zone defense, an uncharacteristic move for Krzyzewski, the Blue Devils have won seven of eight. Before that they had dropped three of four. "We're just growing. We're still learning," Krzyzewski said.
BATTLE FOR BROOKLYN
Duke is 7-0 at Barclays Center, including last year's unprecedented four-game run to win the first ACC Tournament held in Brooklyn. Notre Dame dropped to 9-3 at Barclays.
BEEN A WHILE
Duke has won six straight against North Carolina in the ACC Tournament since the Tar Heels took the 1998 championship game.
Notre Dame: On the bubble, and a big story, when Selection Sunday rolls around.
Duke: A semifinal matchup with North Carolina for the second year in a row. Last season, the Blue Devils won 93-83 to improve to 13-8 against the Tar Heels at the ACC Tournament. UNC rebounded to win the national championship, though. The schools split their two regular-season meetings this year, with each winning at home - including Duke's 74-64 comeback victory last Saturday night.
More AP college basketball: https://collegebasketball.ap.org and https://twitter.com/AP_top25
Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.