ST. LOUIS -- Auburn's offense was flowing at the end of the first half. Desean Murray hit his third 3-pointer and ripped off five straight points to put the Tigers up 41-31 over the Crimson Tide at halftime.

Then, the Collin Sexton show started.

Sexton scored 31 points and No. 9 seed Alabama used a strong second half to defeat No. 1 seed Auburn 81-63 Friday in the quarterfinals of the SEC Tournament.

The Crimson Tide started the second half on a 28-3 run keyed by three consecutive 3s by Sexton. Alabama's surge put the Tigers away early in the half, and the Crimson Tide (19-14) outscored Auburn 50-22 after the break.

"I didn't raise my voice," Alabama coach Avery Johnson said. "I used understandable English, no bad words, and we just talked about how we needed to improve in the second half, and they did it."

Mustapha Heron led Auburn (25-7) with 18 points, 11 of which came in the first half. Desean Murray scored 15 points, all in the first half. The Tigers moved the ball well on offense and drilled seven 3s in the first half.

By the time halftime arrived, it was all Sexton. The freshman scored 21 second-half points. The performance came after he scored 27 points and hit the game-winning shot against Texas A&M on Thursday.

Auburn's shooting struggles continued. Jared Harper finished 2 of 11 with seven points. Bryce Brown shot 1-for-8 from beyond the arc. The Tigers shot just 24 percent in the second half and 1-for-14 from 3-point range.

"It was a tale of two halves," Auburn coach Bruce Pearl said. "We did what we wanted to do in the first half. At the start of the second half, they came down and flipped the table on us really quickly."

Alabama came into the SEC Tournament on a five-game losing streak and in danger of falling out of NCAA contention. But after dominating Auburn, the Tide are at 19 wins and have won six ranked games this season. Johnson made his pitch to the committee following the game.

"We feel we have one of the most impressive resumes with any team in the country with all our top-25 wins, quadrant-one wins, winning on a neutral floor, back-to-back games in the SEC Tournament against two outstanding teams that are projected and supposedly already in the tournament," he said.

"When we came in this tournament, we had to win games," Sexton added.

Alabama takes on Kentucky in the tournament semifinals Saturday at 1 p.m. ET on ESPN.

Auburn waits to see its postseason fate on Sunday.