Cal State Fullerton, which beat Stanford in the NCAA regional final at Sunken Diamond last year, this time has put the Cardinal on the brink of elimination.

Pinch hitter Jace Chamberlin hit a walk-off home run to right center off Will Matthiessen in the ninth inning to give the Titans a 2-1 win Saturday night.

It was the 6-foot-4, 240-pound freshman’s first home run of the season and only the 12th for the Titans, who were designated the home team.

The Cardinal (45-11) will play Baylor Sunday at 1 p.m. in an elimination game. The winner of that game will play Fullerton (34-23) at 6 p.m. If another game is needed, it would be played Monday at 7 p.m.

In the afternoon game, Baylor (37-20) broke open a tight game with seven runs in the last two innings and eliminated Wright State (39-17) 11-5.

The nightcap was the second straight walk-off decision involving Stanford. It won Friday night’s game against Wright State on Christian Robinson’s double in the 13th. This time it was the other team that walked off with the win.

“ That’s two classic ballgames we’ve played in a row,” head coach David Esquer said. “The tale of this one obviously was we had a number of opportunities to score runs and get a big swing — and they got the big swing.”

It was mostly a pitchers’ duel between Cardinal lefthander Kris Bubic and Titans righthander Tommy Wilson.

More Information Stanford regional Sunday: Stanford (45-12) vs. Baylor (37-20), 1 p.m.; Cal State Fullerton (34-23) vs. Stanford-Baylor winner, 6 p.m. Monday: Early-game winner vs. later game loser, 7 p.m. (if necessary) Format: Double elimination See More Collapse

Bubic, in his longest stint in his last seven starts, gave up three hits, one run and two walks in seven innings while striking out 10. He threw 130 pitches.

It was “as good as I’ve ever seen him,” Esquer said.

“The whole second half of the season for me has been kind of a grind, kind of a battle,” Bubic said, “but it’s a new season once you get to regional play.” The idea is “just keeping that aggressive personality and (to) not try to be so perfect.”

Bubic had the distinction of striking out four batters in the second. Jake Pavletich reached first on a wild pitch on strike three, and Bubic fanned the next three.

Wilson, a freshman, gave up just three hits and one run in six innings, striking out six without a walk.

“He rode that fastball up, and we had a lot of flyballs and popups,” Esquer said.

Hank LoForte, the Titans’ 5-foot-6 sparkplug, led off the game with a single and eventually scored on a sacrifice fly by Daniel Cope. Fullerton didn’t score again until the ninth, when Chamberlin got hold of a 2-0 fastball.

Fullerton head coach Rick Vanderhook said Chamberlin’s nickname is “Jumbo” because when the team visited New Orleans to play Tulane this year, he “loved jumbalaya so much.”

It was only the fourth loss for Stanford in 35 home games this season.

The only hit off Wilson through five innings was a double by Nico Hoerner in the fourth. In the sixth, however, Alec Wilson doubled and scored on a triple by Tim Tawa to tie the score.

Stanford was in great position to go ahead later that inning, with a runner on third and one out with Hoerner coming up. But third baseman Brett Borgogno grabbed Hoerner’s sharp grounder and dived to retire Tawa before he could get back to the bag.

Cardinal left fielder Kyle Stowers preserved the tie in the bottom of the sixth by throwing out Mitchell Berryhill at the plate following a single by Valenzuela. Berryhill had walked and stolen second.

Another great chance for Stanford went by the wayside in the eighth. With runners at first and third, Stowers grounded into a 4-6-3 double play to end the inning. Esquer protested the call at first, and video replays indicated Stowers barely beat the throw.

Briefly: Stanford second baseman Beau Branton was hit in the face by catcher Christian Molfetta’s one-hop throw in a vain attempt to keep Berryhill from stealing in the sixth. Branton remained in the game. … Bubic picked Ruban Cardenas off first in the third inning, but Cardenas forced an extended rundown, the play going 1-3-6-3-4-6-3-1.

Tom FitzGerald is a San Francisco Chronicle staff writer. Email: tfitzgerald@sfchronicle.com Twitter: @tomgfitzgerald