Updated

Bucknell made its run.

Problem was, Butler responded with an even bigger one.

Joe Willman had a career-high 20 points, and Cameron Ayers made two big 3-pointers during a 19-2 spurt that gave Bucknell a 6-point lead midway through the second half. But the Bison went nearly five minutes without scoring and had no choice but to foul Butler down the stretch in a 68-56 loss that was closer than the final score indicated.

"It doesn't feel good," Willman said. "It just sort of hits you that that's your last game, the last time putting on a Bucknell uniform. It's unfortunate. It happens."

At least the 11th-seeded Bison (28-6) can take comfort in the knowledge that, when Butler's involved, it happens a lot.

Rotnei Clarke scored 11 of his 17 points in the last 8:44, including five at the free throw line. Andrew Smith, one of two starters left from the Butler teams that reached the 2010 and 2011 NCAA title games, had a double-double with a career-high 16 rebounds and 14 points. Roosevelt Jones also had 14 points for the sixth-seeded Bulldogs (27-8), who have won 11 of their last 13 games in the NCAA tournament.

"I just think they played in so many big games that they're not the type of team that's going to get rattled," Bucknell coach Dave Paulsen said.

Butler's title game runs gave hope to little guys everywhere — the Bulldogs nearly knocked off Duke in 2010, with Gordon Hayward's half-court heave clanking off the rim — and Bucknell hoped to pull off an upset of its own Thursday. They had it in their DNA, having knocked off third-seeded Kansas in 2005, one of the tournament's classic upsets.

And the veteran team has come a long way from the squad that was blown out by eventual champion Connecticut two years ago.

But the Bulldogs stifled two-time Patriot League Player of the Year Mike Muscala, with Smith and Khyle Marshall swarming him anytime he got within a thought of the paint. He was limited to a measly two points in the first half, a smooth jumper in the opening seconds of the game, and finished with nine. It's only the second time this season he's failed to reach double figures.

The Bison didn't get a lot of help from their other 1,000-point scorers, with Ayers and Bryson Johnson also finishing with nine.

"We wanted Andrew rotating to Muscala, we wanted Andrew in the middle of the paint," Butler coach Brad Stevens said. "It's one of the reasons why we were late to Willman quite a bit. But you've got to give up something."

Willman single-handedly kept Bucknell in the game, hitting one jumper after another from deep in the corner. But when Khyle Marshall made a jumper to give Butler a 29-18 lead with 16:35 left, it looked as if the Bulldogs were on the verge of pulling away.

"We knew they were going to make a run," Smith said.

Sure enough, Muscala converted a three-point play to spark a 19-2 run.

Just as he'd carried Bucknell the first half, Willman was key during the spurt, scoring eight points. When he made a jumper to put Bucknell up 32-31, its first lead since the opening seconds of the game, he jumped up and down and then quickly composed himself.

"When we were making that run, we were really confident," Willman said.

But as anyone who's watched Butler the last few years knows, this one was far from over.

The stars from Butler's title runs are gone — Smith and Marshall are the only starters who are carryovers — but the way the Bulldogs play remains the same. Turn up the heat defensively, take advantage of opportunities on offense and never, ever quit.

"The similarity is they're Butler," Stevens said. "They have some mettle. They have some intestinal fortitude built up over time. The difference is just the people."

Smith made a 3, then Marshall stripped the ball from Muscala at the other end and fed Clarke, who hit another 3 to put Butler back in front 39-37. After a three-point play by Ryan Frazier, Smith scored on a hook shot. Pesky Alex Barlow got another steal — he had four for the game — and scored on the driving layup to give Butler a 43-40 lead with 7:28 to play.

Willman's jumper cut Butler's lead to 43-42 with 6:56 left, but the Bison went the next 4:42 without scoring. Butler, meanwhile, was putting on a free throw clinic, making 18 of 20 to seal the victory.

"This one stings," Paulsen said. "We made our run in the second half, and they came up with the big plays down the stretch."