SANTA BARBARA, Calif. -- Sophomore catcher Paddy O'Brien stroked a pinch-hit walk-off single into shallow center field in the 13th inning of Sunday's contest at Caesar Uyesaka Stadium, scoring Kyle Plantier to give UC Santa Barbara a 4-3 win and a sweep of visiting UC Davis.

Freshman southpaw Kyle Nelson (3-1) picked up a very deserved win, tossing five hitless innings of relief with five punchouts. A San Francisco native, he retired all 15 batters he faced without allowing a single baserunner.

UCSB's record improved to 34-10-1 (11-4 Big West) with the win, putting it in a tie for first place with idle UC Irvine and Cal State Fullerton. The Aggies, who have now lost 10 consecutive games to the Gauchos, fell to 26-19-1 (5-10).

This was also the third walk-off win of the season for UCSB, which previously accomplished the feat against Southern California on March 3 and Dartmouth on March 21.

Plantier, who plated the game-winning run, led off the 13th by slicing a base hit back up the middle, moving to second on Andrew Calica's sacrifice bunt attempt. With one out, freshman shortstop Clay Fisher had a chance to knock in the run, but the Gauchos had to settle for Plantier moving up a base on a groundout.

O'Brien then entered the game as a pinch-hitter for Wear, and he immediately validated that move, lining an 0-1 pitch over the UCD second baseman's head to send the Gauchos home happy.

The Gauchos actually had a golden opportunity to end the game an inning prior, as they put two runners on with no outs. However, an unsuccessful sac bunt attempt and a double play snuffed out the potential rally.

UCSB had led for the majority of the game thanks to a three-run second inning, highlighted by Fisher and Cameron Newell RBI singles and a Peter Maris sac fly.

However, the Aggies chipped away at that lead, plating two runs in the fifth and then tying the game in the eighth when Tanner Biley scored from third on an Austin March groundball.

As pivotal as Nelson was in the Gauchos win, UCD's Spencer Henderson was just as effective for the Aggies, fanning eight and allowing just two hits in six excellent innings of relief.

For UCSB, starter Shane Bieber allowed three earned runs on six hits with six punchouts in eight innings of work. UCD's Max Cordy struggled a bit, allowing three runs and eight hits in four innings, but the Aggies were stablilized once Henderson made the switch from the DH spot.