Thurman allowed six hits in six innings to improve to 2-3 and Hooper threw 2 1/3 hitless innings to record his first save.
Senior left fielder Drew Hillman was three for four with three runs batted in. He had two doubles.
Junior designated hitter Jordan Leyland was two for five with three RBIs and senior third baseman Brian Hernandez was three for five to pace UCI's 14-hit attack.
UCI (27-12), scored four in the first, tied the score with two in the third, then scored two in the fourth and one in the fifth to take command.
The series rubber game is Sunday at 1 p.m.
IRVINE — Vanguard University scored three runs in the 10th inning to post an 8-5 win in Game 1, but host Concordia rallied for a split in Golden State Athletic Conference play on Saturday.
Jerry Peña and Darrell Hudson had back-to-back RBI singles with the bases loaded to key the opening-game win for the Lions, who conclude the season 22-26, 16-20 in conference.
Jeremiah Mejia hit a three-run home run for the Lions in Game 1, then went two for three with one RBI to key the visitors' five-hit attack in a 6-1 loss in Game 2.
Concordia is 31-18, 20-16.
WOMEN'S WATER POLO
UC Irvine 15, UC Davis 9
SANTA BARBARA — Danielle Warde scored five goals and Jessy Cardey added four to help the Anteaters win the Big West Conference Tournament semifinal Saturday at UC Santa Barbara.
No. 10-ranked UCI (20-8) bids for its third straight conference tournament crown and an automatic berth into the NCAA Tournament, when it faces No. 16-ranked Long Beach State (13-16) in the title game Sunday at 2:30 p.m.
Long Beach State upset No. 2-seeded Cal State Northridge, 7-6, in overtime in the other semifinal Saturday. The 49ers upset host UCSB, 4-3, in the opening round on Friday.
Warde and Cardey each have 50 goals this season for UCI, which outscored the Aggies, 5-1, in the third quarter to pull away after holding a 7-6 halftime edge.