CLEMSON, S.C. -- K.C. Rivers knows it's not Clemson's shooting touch or fastbreak attack that's fueling its latest unbeaten streak.

"We call it mental focus," said Rivers, the team's senior captain. "When you want to do something, you've got to focus in on doing it and (coach Oliver Purnell) has made us focus in on stopping on defense. And that's what we did. We bought in."

It was the defensive focus, along with Trevor Booker's 19 points, that kept the 12th-ranked Tigers only one of three Division I unbeatens with a 66-59 victory over Alabama on Tuesday night.

The Tigers kept pace with their 17-0 run of two years ago. But that dissolved into an abyssmal 2-9 stretch once Atlantic Coast Conference play began.

This group showed off a consistently frenetic defense that helped turn a close game into a runaway in the second half. Clemson joins No. 1 Pittsburgh (14-0) and No. 4 Wake Forest (13-0) as the only Division I teams left without a loss after Illinois State dropped its first game of the season to Bradley, 56-52, on Tuesday night.

Clemson looked like it would fall off, too, as the Crimson Tide overcame a six-point deficit at the half to lead 42-41 on Yamene Coleman's basket with 14:16 to go. Then Clemson set off on 14-0 run to take control. Rivers had two jumpers in the stretch while Terrence Oglesby made a runner and a 3-pointer.

After Senario Hillman hit a free throw to break Alabama's drought, freshman Andre Young made a three to give Clemson its largest lead, 58-43.

The Crimson Tide managed only one basket between Coleman's shot and JaMychal Green's bucket with 1:45 left, missing 10 straight shots.

Rivers got it started with a basket and Andre Young followed with a 3-pointer. Rivers struck again to make it 48-42. Terrence Oglesby scored the next five points while Demontez Stitt ended the surge with a driving bucket.

Hillman ended Alabama's drought with a foul shot. But Young answered with another 3 to push Clemson to its biggest lead, 58-43.

"We got the key stops that got us the insurmountable lead," Rivers said. "Defense is what's going to win it for us."

It's hard to argue.

Alabama (10-4) missed seven of eight shots during a stretch of the opening half and 10 in a row during Clemson's decisive run.

Ronald Steele was held to 10 points, none in the second half when the Tide needed someone, anyone, to step up and score.

Still, Alabama coach Mark Gottfried was pleased with his team's effort. "Our guys fought hard," he said. "Clemson is good if they find a pocket where they can make a run and that's what they did in the second half."

Alabama made a late run, too, cutting the lead to 64-59 in the final 10 seconds, but it was too late to save its five-game win streak.

Clemson stayed perfect throughout its nonconference schedule. The Tigers jump back into the Atlantic Coast Conference on Saturday against North Carolina State.

Tiger coach Oliver Purnell congratulated his guys on the achievement. "At the same time, we've got to realize that there's still work to do, and some of those things showed up tonight," he said.

Rivers added nine rebounds, four steals and three assists. Oglesby also had 12 points.

Hillman and Alonzo Gee had 12 points each to lead Alabama, which had just come off an 88-77 victory over Georgia Tech. Early on, the Tide looked ready to knock off a second straight Atlantic Coast Conference opponent.

Steele, coming off a 23-point performance in the Georgia Tech win, hit a pair of 3-pointers to put the Crimson Tide out front, 12-5.

Alabama was still up 20-17 after Steele's jumper with 9:06 left in the half. That's when Clemson's defense kicked in and fueled an 11-3 run.

Booker had a basket and finished a three-point play after his fade-away jumper. Rivers finished the surge with a long 3-pointer with a second left on the shot clock.