LAS VEGAS – The bromide is that it’s tough to beat a team three times in a season.

That appeared to go out the window Monday when top-seeded Saint Mary’s, after two down-to-the-wire finishes against BYU in the regular season, built a 26-point lead 5 minutes into the second half.

The fifth-seeded Cougars made those last 15 minutes tough on the Gaels, who hung on for a 76-69 victory to advance to the West Coast Conference championship game for the sixth time in eight years.

Saint Mary’s (26-6) never trailed, made 50% of its shots and closed the first half with a 10-0 spurt to take a 37-20 lead. The Gaels were up 56-30, but BYU made things interesting by hitting 64.3% of its shots in the closing 20 minutes.

Alex Ducas made four 3-pointers and scored 23 points and Aidan Mahaney added 18 points for the 16th-ranked Gaels. Spencer Johnson led the Cougars with 13 points.

“You don’t want to have to try to beat BYU a third time,” Gaels coach Randy Bennett said. “They’re pretty talented team and they just won two games in this tournament. We played well for the first 25 minutes and then I think we lost focus a little bit.”

BYU (19-15), who will join the Big 12 Conference next season, exits the WCC without a regular-season or tournament title in 12 seasons.