A A week ago, Saint Mary's was riding the nation's longest winning streak at 19 games, heading toward a probable No. 2 seed in the NCAA Tournament and sitting on top of the West Coast Conference standings getting ready for a showdown with arch-rival Gonzaga.

How quickly things change in the world of college hoops.

The Gaels' winning streak came to a crashing end on Feb. 10 when Gonzaga came to Moraga, Calif., asserted its dominance from the start and crushed Saint Mary's.

On Thursday, the No. 15 Gaels had a chance to start a new streak when they faced a San Francisco team it had defeated two weeks earlier by 36 points. On paper, it was a mismatch.

The Gaels (24-4, 13-2 WCC) did start a streak -- but not the kind they wanted as they now have lost two straight after being upset by the Dons 70-63.

Saint Mary's, which appeared to be a lock to reach the NCAA Tournament, finds itself in a bit of trouble with Portland on deck Saturday in Portland, Ore.

"We just have to do some things to help our guys get our confidence back," St. Mary's senior point guard Emmett Naar told SFgate.com.

Senior center Jock Landale scored 19 points to lead the Gaels against the Dons, but for the second straight game, his teammates were unable to produce when their best player struggled.

"We have to play better when we're without him," Saint Mary's head coach Randy Bennett told reporters. "He hasn't had much foul trouble all year. They called three offensive fouls on him, one post-up, two illegal screens when he had the ball in his hands. You don't get those very often but it is what it is. We have to be good enough to play through it."

Landale also became the fifth player in Saint Mary's history to record at least 1,500 points and 700 rebounds.

The Gaels won't be taking the Pilots lightly, even though they won the first meeting 72-55 back on Jan. 27. Jordan Ford scored 20 points to lead the Gaels to what was their 16th straight win, a school record at that time.

Portland might be a bit emboldened after seeing the Dons pull off the upset and will study how Gonzaga took Landale out of the game with hard double teams.

The Pilots (10-18, 4-11) have lost three in a row and are coming off an 81-72 setback Thursday to Santa Clara. Former Portland Trail Blazers star and Pilots head coach Terry Porter is preaching a positive culture -- win or lose.

"Early in the year, we had turnovers by our young guys in late-game situations that we didn't do a good job of executing," he recently said. "And we learned from those. We've done a much better job in all of these games of executing down the stretch at both ends of the floor."

Porter is mentoring a pair of young guards, freshman Marcus Shaver Jr. and sophomore Josh McSwiggan. Shaver leads the team in scoring at 11.8 points per game and McSwiggan comes in at 11.2 points per game.

Another freshman, Tahirou Diabate, has shown improvement of late. The Mali native has started the past 11 games and scored 19 points in a Feb. 1 overtime victory over Pepperdine.

"He's stuck to the grind and learned and been really receptive to what everyone had to tell him. He is an example of our growth as a team," senior wing D'Marques Tyson said. "Earlier in the season, he would have been worried about where he needed to be and not worried about protecting the rim. He realizes that now and embraces his role and is a solid rim protector."

He has eight blocks over the past five games.