The Arizona sophomore and Pac-10 Player of the Year made his second in as many tournament games Sunday night, completing a three-point play with 9.6 seconds remaining to lift the Wildcats to a 70-69 win over Texas.

Williams also had the saving block with 2 seconds remaining in Arizona’s opening 77-75 win over Memphis on Friday. He struggled for much of the game Sunday but finished with 17 points, including the final three.

“I wasn’t surprised by the block against Memphis,” Williams said. “I am a little surprised by the shot I made today. I haven’t seen the replay yet, but I wasn’t looking at the basket. I was looking down so I wouldn’t have a hard fall.

“I was surprised it went in, but at the same time I’m glad it went in.”

The win lifts the No. 5 seed Wildcats (29-7) into a regional semifinal matchup with top-seeded Duke on Thursday. It marks a triumphant return to the second weekend of play in the school’s first trip back to the tournament after last season’s absence ended its 25-year appearance streak.

“I can’t tell you how excited we are to be moving on to the Sweet 16,” second-year Arizona coach Sean Miller said. “It’s one thing to be a part of this tournament, but when you have the experience of advancing, it’s second-to-none as a college basketball program, players, coaches.”

The win over the No. 4 seed Longhorns didn’t come without its share of controversy. Texas (28-8) trailed by as many as 13 points in the first half before J’Covan Brown scored 21 of his 23 in the second to lead the Longhorns back into the game.

Brown was 13 of 13 on free throws, bringing his two-game tournament total to a perfect 25 of 25. His jumper in the lane with just over a minute remaining gave Texas a 69-67 lead, its first since it was up 12-11 early in the game.

The shot appeared as though it would keep the Longhorns in the lead for good after Williams misfired on a go-ahead attempt with 14.5 seconds remaining. Texas freshman Tristan Thompson blocked the attempt, which Jordan Hamilton corralled before calling a timeout for the Longhorns.

Following the timeout is when the fun began, at least for Arizona. Texas’ Cory Joseph struggled to inbound the ball against the swarming Wildcats defense and appeared to call a timeout.

However, referee Richard Cartmell called Joseph for a five-second violation, though replays showed he appeared to make the call before reaching five.

“I had five seconds before the kid turned and signaled a timeout,” Cartmell said in a statement. “I had to make a decision whether it was five seconds or a timeout, and I made the decision it was five seconds because I had counted five seconds before he called timeout.”

Texas coach Rick Barnes only wished afterward that replays could have been used to determine if the correct call had been made.

“They have rules in other leagues and even on an out-of-bounds play,” Barnes said. “There are certain things that can be corrected. In our game, there’s not.

“We’ve got to be willing to make the rules that are right. Because at the very end if you truly want the players to determine it, the officials have to be willing, the NCAA has to be willing to say, OK, we’re going to get this right.”

The Wildcats took advantage of their second chance. Following the inbound, Williams set a pick for Kyle Fogg and slipped underneath the Texas defense before receiving a pass from Fogg. Williams then drove the baseline and made the blind shot to tie the game at 69 while being fouled by his former AAU teammate Hamilton.

“To be honest, I didn’t even feel contact at all,” Hamilton said. “But the ref made up his mind and called a foul. There’s nothing we can do about it now.”

Williams’ free throw put Arizona up 70-69 with 9.6 seconds remaining, leaving plenty of time for one final chance for the Longhorns.

Brown brought the ball up the court and drove into the lane and a trio of Wildcats defenders, including Williams. His wild shot went high off the glass and missed, leaving a mad scramble for the ball underneath the basket as time expired.

“Every player’s going to think he got fouled in that situation, but it’s hard for the refs to call it when the game’s on the line,” Brown said. “But things happen. I’m just trying to move on from it.”