Matt McCarthy gave San Francisco the lead for good on a layup with 4:32 to play, and the Dons held on down the stretch Thursday night for a historic 70-63 upset victory over 15th-ranked Saint Mary's in a West Coast Conference shocker in San Francisco.

The win was the first for the USF (15-13, 7-8 WCC) over a ranked team since they beat 24th-ranked Gonzaga on Feb. 18, 2012. The Dons had lost 16 in a row to ranked opponents since then.

Saint Mary's (24-4, 13-2) dropped out of a first-place tie with Gonzaga (14-1) with just three games remaining.

The Gaels had embarrassed USF 79-43 in an earlier meeting in Moraga, Calif. The 43 points represented the season-low for both USF and a Saint Mary's opponent.

Saint Mary's led by as many as 11 points in the rematch, 27-16, on an Evan Fitzner layup with 7:34 remaining in the first half.

But the Dons, who entered the game just 3-3 at home in conference play, closed within 38-35 by halftime, then battled the powerful Gaels on better-than-even terms throughout the second half.

McCarthy's critical hoop came after Saint Mary's star Jock Landale gave the Gaels their final lead of the night at 56-55 with a pair of free throws with 4:43 remaining.

Frankie Ferrari hit two key hoops down the stretch for the Dons, who pulled away in the final seconds with six free throws.

Ferrari had a game-high 20 points to lead the Dons, who had gone 0-4 against ranked opponents this season, losing those games by a total of 73 points.

Ferrari hit seven of his 11 shots and found time for a game-high seven assists.

Jordan Ratinho added 13 points for USF, while reserve Jimbo Lull contributed 10 points and a game-high seven rebounds to the win.

USF outshot Saint Mary's 46.0 percent to 42.9 percent.

Landale had a team-high 19 points for Saint Mary's, which was coming off a 78-65 home loss to Gonzaga on Saturday that had created the tie atop the conference standings.

Fitzner finished with 17 points and Emmett Naar 16 to complement a team-high five assists for the Gaels, who took their first road loss in conference play after seven wins.

The Gaels shot just 4-for-14 from 3-point range.

--Field Level Media