LONG BEACH STATE -- Clayton Allison threw a five-hitter, Tommy Mendonca drove in four runs, and the Fresno State Bulldogs advanced to the championship round with a 6-0 NCAA regional baseball win over No. 6 San Diego on Saturday night at Blair Field.

Allison (3-5) struck out three, walked one and allowed no Torero past second base.

"The eight guys behind me deserve the credit,'' Allison said. "They made some big plays and really kept the game moving along. When we play defense like that, we feel we can win every time out.''

Allison opened with five perfect innings -- a string that ended when Victor Sanchez singled off the glove of third baseman Mendonca to start the sixth.

Sean Nicol's double was the only extra-base hit San Diego (42-16) managed off Allison.

Mendonca, meanwhile, went 2-for-3, connecting for a three-run double in the fourth and an RBI single in the sixth. The sophomore was back in action one day after leaving his team's 7-3 victory over Long Beach State with a hand injury.

"We had a lot of guys step up and play big,'' Fresno State coach Mike Bartesole said. "Tommy was one of those guys. Frankly after last night I never expected we would have him back. He's a tough kid and showed it tonight."

Erik Wetzel was 2-for-4 and scored twice for the Bulldogs, who dealt San Diego's Josh Romanski his first loss of the season.

Romanski (9-1) went the distance, giving up six hits while striking out six and walking one.

The fourth-seeded Bulldogs (39-27) will try to lock up a regional championship tonight at 5, when they play the winner of a 1 p.m. elimination game between top-seeded Long Beach and second-seeded San Diego.

If Fresno State loses tonight, a second game will be played Monday at 6 p.m.