LEXINGTON, Ky. — Sorry, Bucknell. This year’s Butler is still Butler.

Andrew Smith had a double-double with a career-high 16 rebounds and 14 points, and Butler made 18 of 20 free throws down the stretch to hold off upset-minded Bucknell 68-56 in the second round of the NCAA tournament on Thursday. Roosevelt Jones added 14 points for the sixth-seeded Bulldogs, back in the tournament for the first time since making back-to-back runs to the national title game.

Leading scorer Rotnei Clarke was just 5-of-14. But he went 5-of-6 from the line — all in the final 2:59 — and finished with 17 points in his first appearance in the NCAA tournament.

Joe Willman had a career-high 20 points, and 11th-seeded Bucknell made a game of it with a 19-2 run in the second half. But it couldn’t overcome an off day by two-time Patriot League Player of the year Mike Muscala, who had nine points, only the second time this season he’s failed to reach double figures. Going almost five minutes without scoring late in the second half didn’t help, either.

Butler (27-8) will now face the winner of Davidson-Marquette on Saturday in the East Region.

Little Butler’s appearances in the championship game gave hope to little guys everywhere — they 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 have it in their DNA, having knocked off third-seeded Kansas in 2005, one of the tournament’s classic upsets.

And for a while, it looked as if Bucknell might just beat Butler at its own game.

The Bulldogs appeared on the verge of pulling away when Khyle Marshall made a jumper to give Butler a 29-18 lead with 16:35 left. But Muscala, who’d been downright dismal for the first 24 minutes of the game, 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.

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

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 Frazier’s three-point play, Smith scored on a hook shot and pesky Alex Barlow got another steal and scored on the driving layup to give Butler a 43-30 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.