SAN DIEGO -- It took a 1-3-1 zone defense, of all things, for No. 10 San Diego State to complete a remarkable comeback against No. 21 New Mexico that clinched the outright Mountain West Conference title.

SDSU was getting manhandled inside by New Mexico's big men, Cameron Bairstow and Alex Kirk, and fell behind by 16 points with 12:05 to play.

Coach Steve Fisher finally agreed with assistant coach Justin Hutson's suggestion to go to a 1-3-1 zone. The game turned just like that, with SDSU going on a 19-1 run that helped it win 51-48 Saturday night.

After Hutson initially suggested the zone, Fisher was hesitant, so the Aztecs didn't go to it.

"So after another dunk and a layup and a dunk, I said, `Timeout. We're going to the 1-3-1,' Fisher said, referring to, of course, to baskets by Kirk and Bairstow. "For some crazy reason, it worked. They no longer were able to pull the ball into the low post. I know they were taken off guard, so were our kids. It got us obviously back into the game.

"We fought and fought and fought and made plays," Fisher said. "We got a super, super win that was obviously tremendously important. The winner hangs a banner, the loser is the loser. The two best teams played and tonight we found a way to get a win."

Xavier Thames scored 23 points for SDSU (27-3, 16-2), which clinched the No. 1 seed in the conference tournament in Las Vegas. Josh Davis, SDSU's other senior, had nine rebounds and six points, including some big plays during the 19-1 run that pulled the Aztecs back into the game.

Thames and Matt Shrigley each made two free throws in the final 9 seconds to keep the Aztecs ahead.

The fans rushed the court and black and red confetti fell from the ceiling at Viejas Arena, where the Aztecs were 15-1 this season. Their only home loss was to Arizona on Nov. 14.

The Aztecs, who have earned at least a share of the MWC title three times in four years, can go entire seasons without playing zone. They first used one this season when they rallied from 14 points down at Boise State on Feb. 5 to win 67-65.

"That's the only zone we have in right now," Fisher said, who added that the Aztecs usually stay in zone for only one possession, not long stretches. "Even I thought we defended them well, but they're big and strong and good. ... No harm, no foul when you're down by 16 and it doesn't seem like we have a chance."

How did the Aztecs do it?

"The same way we always do -- with defense," Winston Shepard said.

"That was tough," New Mexico coach Craig Neal said. "They went zone and we just didn't make the adjustment. We had some players, like Kendall Williams in foul trouble, and we couldn't guard Thames. Thames got it going and our defense wasn't the same. You've got to give them credit; they played well. We just couldn't make the adjustment and make things happen."

Bairstow scored 20 points and keyed two big runs for New Mexico (24-6, 15-3).

With SDSU leading 47-45, Williams, last season's Mountain West player of the year, missed a 3-point shot with 9 seconds left for the Lobos.

Thames rebounded and was fouled by Kirk, making both for a four-point lead. Thames had a steal and Shrigley was fouled by Cullen Neal, making both for a 51-45 lead. Williams made a 3-pointer with 1 second left.

New Mexico led 41-25 after Kirk made a turnaround jumper with 12:05 left, capping a 15-0 run in which he and Bairstow did most of the scoring.

But the Aztecs came racing back with an airtight defense and big scoring plays by Thames, Davis, Shrigley and Dwayne Polee.

New Mexico made its first field goal in more than seven minutes when Deshawn Delaney made a 3-pointer for a 45-44 lead.

Thames hit a jumper to give SDSU a 46-45 lead. Kirk missed two free throws with 59.1 seconds left and Davis rebounded the second miss. JJ O'Brien made the first of two free throws to give SDSU a two-point lead.

Thames had five steals and Polee four.

Bairstow had scored 26 points in a 14-point New Mexico win against the Aztecs in Albuquerque two weeks earlier.

The Lobos ended the first half on a 15-2 run to take a 26-20 lead. Bairstow had seven points in the run, including a long jumper at the buzzer, and fed Kirk for easy shots on consecutive possessions.

Bairstow had 13 points in the first half and Kirk nine. The only other Lobos to score in the first half were Kendall Williams and Neal with two points apiece.

Earlier, the Lobos went 8 1/2 minutes in between field goals as SDSU went on 12-0 run fueled in part by Josh Davis' rebounding. Davis had a coast-to-coast layup while Shepard had a three-point play and a twisting jumper to give SDSU a 16-9 lead. New Mexico finally scored when Neal made a layup.