College of Idaho pushed across two runs in the bottom of the eighth inning to beat host Menlo, 5-4, on the first day of the NAIA West Regional.
The Oaks (32-15) play an elimination game Thursday at 3 p.m. against the survivor of an earlier game between Patten and Simpson.
Menlo took a 4-2 lead in the fourth against Idaho's undefeated Mitch Dame (9-0), who completed his fifth game of the season.
Joel Hull hit a pair of solo home runs for the Oaks and C.J. Dailey drove in two runs. Paulo Oakley and Michael Brandi each added two hits.
Derek Martinez pitched seven innings, allowing four runs on seven hits. He struck out six and walked two. Kyer Vega (4-2) gave up the go-ahead run.
College of Idaho and British Columbia meet at noon Thursday, with the winner advancing to Friday's championship game.