ESPN Men's Basketball

DAYTON, Ohio -- With his team in the midst of the biggest comeback in NCAA tournament history, BYU coach Dave Rose caught the look in his players' eyes and was reassured.

A rally for the ages was in the making.

Noah Hartsock scored 16 of his 23 points in the second half and the Cougars came back from 25 points down to beat Iona 78-72 in the first round Tuesday night.

During a timeout after the Cougars had pared the lead to single digits midway through the second half, Rose saw something he'll never forget.

"The look in our players' eyes at that time was, 'Game on. We've got a chance here,' " Rose said. "And we were able to finish it off."

Brandon Davies added 18 points and Damarcus Harrison 12 for the 14th-seeded Cougars (26-8), who advanced to play third-seeded Marquette on Thursday in Louisville, Ky.

It marked the biggest comeback in an NCAA tournament game, the organization said. Previously, the largest deficit overcome was 22 points in 2001 when Duke fought back to beat Maryland 95-84 in the national semifinals.

There was no consolation for Iona.

"It's going to be one that we have to live with the rest of our lives," Gaels coach Tim Cluess said. "It's a tough one we let get away. No excuses."

It was the second incredible turnaround of the night in Dayton. With President Barack Obama and British Prime Minister David Cameron watching, Western Kentucky came back from a 16-point deficit in the final 5 minutes to beat Mississippi Valley State 59-58.

That was the biggest margin overcome by a team in the final 5 minutes to win an NCAA tournament game, the organization said.

Hartsock was a little hurt that the president wasn't around to see the fireworks in the nightcap.

"I started looking around and didn't see him," Hartsock said with a grin. "But I'm sure he had some important things to take care of."

Iona (25-8) seemed assured of its first official NCAA tournament victory after dominating the first half. But despite 15 points and 10 assists by Scott Machado, the Gaels dropped to 0-8 in NCAA play. Their lone win in 1980 was vacated due to NCAA violations.

Iona came in as the nation's top-scoring team at 83.2 points per game and didn't disappoint -- at least in the opening 16 minutes. The Gaels scored 55 points in an eye-popping display of passing wizardry and outside shooting. Then they didn't score over the final 4:30 of the first half.

Machado, averaging just under 10 assists a game, had nine at the break.

BYU then took control, slowly but surely. The Cougars held the Gaels without a point for 9:20 in a 17-0 run to narrow the deficit to 62-61 midway through the second half. BYU made up ground with a trapping halfcourt defense that forced the Gaels out of their hurry-up-and-shoot-3s attack. At the other end, the Cougars were getting buckets from Hartsock on fallaway jumpers.

"We just were more aggressive," Cougars guard Brock Zylstra said. "We were doing to them what they were doing to us in the first half."

Iona scored 55 points in the first 16 minutes, then managed just three field goals and seven points over the next 16½ minutes.

Jermel Jenkins ended the lengthy drought with a 3 from the left corner with 8 minutes left.

From there on, the teams traded baskets as the pace slowed. Machado's three-point play pushed the lead to 70-64 with 5 minutes remaining before Hartsock hit an outside shot. After two missed foul shots by the Gaels, he hit another short turnaround jumper to cut the lead to two.

With 2:26 left, Hartsock popped out on the right wing to hit a go-ahead 3. It was the Cougars' first lead of the game.

"This is a team that's worked hard all year, that's never given up," Hartsock said.

Davies added two free throws in the final minute before Zylstra scored in transition and turned it into a three-point play, and the comeback was complete.

It was a shocking turn of events because of how well the Gaels -- who also got 12 points from Mike Glover, 13 from Jenkins and 10 by Sean Armand -- had played at the outset.

"You're looking for answers out there, looking for guys to make a play," Cluess said. "Their good player is drilling it with guys in his face and guys draped all over him. Big-time players have to make big-time plays."

Rose, a co-captain for the old Phi Slamma Jamma teams at Houston, has tasted disappointment before. But not this night.

"It was tough for us early," he said. "But our guys fought. We fought hard. We fought all game long."