This can't possibly go on, can it?

The Arizona Wildcats remained undefeated Thursday by the slimmest of margins once again, after a potential game-winning three-pointer by Colorado's Sabatino Chen was ruled to have been taken a split-second after the regulation clock expired.

From there, Arizona coasted in overtime to a 92-83 win, matching and perhaps even surpassing its dramatic one-point wins against Florida and San Diego State during what is now a 13-0 season.

"I'm speechless," Arizona forward Kevin Parrom said.

The victory not only kept the third-ranked Wildcats unbeaten but gave them their best start in 82 years, and evened at 2-2 what has already been a wild rivalry with Colorado (10-3).

Since the Buffaloes joined the Pac-12 last season, they have beaten the Wildcats by a point in Boulder, Colo., by two points in the Pac-12 tournament final and led Thursday's game by double-digit margins in both halves until a mad scramble in the final minutes.

While there were a number of key plays in the final seconds - including key fouls by Mark Lyons and Xavier Johnson, plus the missing of two free throws by Colorado's Jeremy Adams - Chen's would-be three-pointer is the one that will be remembered the most.

After Lyons hit two free throws with nine seconds left, having gone to the line when Johnson fouled him as he dribbled outside the free-throw line, the Wildcats blanketed most of Colorado's shooters on the final play but left Chen an open-enough window to fire off the potential game-winner.

The shot went off the glass and in, prompting the Buffaloes to mob the normally modest-shooting Chen, but officials ruled the shot was taken after time expired. Although some replays indicated the ball was shot with 0.1 of a second left, official James Breeding indicated to the ESPN crew doing the game that Chen's fingertips were still touching the ball when time expired.

"If it's the wrong call, then I'm really sick to my stomach," Colorado coach Tad Boyle said. "We've got guys in the locker room that deserved to win."

UA coach Sean Miller said during his postgame news conference that he had not seen the replay but was told it could "go either way." He said the same was also true of a foul called on Lyons when Colorado's Spencer Dinwiddie hit the floor. Dinwiddie then made 1 of 2 free throws with 49.7 seconds left to give the Buffs an 80-76 lead.

"You can play that game all the way through, and we've been on the tail end of that call when you say 'Ah, it should have gone our way,'" Miller said. "That's why you play the game all the way to the end."

Miller also not-so-subtly indicated that Chen, a senior who had made only two previous three-pointers in his two-year career, was the guy UA wanted to shoot if anyone had to.

"He did bank the shot in," Miller said. "He was 2 for 23 coming into our game. So there's good fortune on both sides of the ball. … I felt like we earned it."

While the officials reviewed the shot, Miller parked his team in front of his bench for a timeout, as if already preparing for an overtime period. He said afterward that it was "all an act," a subliminal message to the referees that the game should still go on.

But Miller said he wasn't sure which way the call would go, and Lyons, who was the game's leading scorer with 24 points, wasn't either.

"I was so worried about it: Did it count, or didn't it count?" Lyons said. "I didn't know. I saw the ball go in and got a little bit upset, like we worked this hard and (then) for him to bank in the shot."

Still, UA guard Nick Johnson kept some faith, noting that he was near Parrom, who had approached Chen as he shot.

"I knew it wasn't good," Johnson said. "I was just holding to my gut feeling."

While opinions varied about Chen's shot, the Wildcats were in agreement about what would happen next: The overtime, they believed, was theirs.

"Everybody in the gym knew that," Lyons said. "When you're having a home game, and rally back to put the game into overtime, it usually works out in your favor."

Sure enough, Parrom made a three-point play 47 seconds into overtime, putting UA up 83-82 and the Wildcats never trailed again. Lyons had five points in overtime and Solomon Hill, after a rough game in which he had five turnovers and four fouls, capped it with two free throws with 23 seconds left.

Askia Booker, who led Colorado with 18 points, said it was very difficult for the Buffaloes to recover in overtime.

"I think it showed that we didn't recover," he said. "We came out and didn't play defense."

Still, Miller said the Buffaloes are clearly a team that is going to win games in the future, a lot of games.

It's just that, for now, Arizona has a hot hand, a lucky hand, or some kind of magic hand that nobody can quite define at this point.

They had, somehow, moved to 13-0, pulling out an improbable win before a sold-out and hoarse McKale Center crowd.

"Our fans and our team deserve equal credit for doing what they're supposed to, and that is staying until the bitter end," Miller said. "So many crowds get disenchanted at the four-minute mark that they start to leave … our crowd doesn't do that, and we don't either.

"And because we've been in some hard-fought games, I feel like we have a confidence about us late, that we believe we can win. It's not that easy. Players have to make huge plays. It's not all luck. But there is some good fortune."

Up next

• Who: Utah at No. 3 Arizona

• When: 3 p.m. Saturday

• TV: Pac-12 Arizona

• Radio: 1290-AM, 107.5-FM, 990-AM (Spanish)