UCI (14-3), ranked No. 11 by Collegiate Baseball, scored three in the fourth to pull even when Jonathan Hurst singled in two and Tommy Reyes worked a bases-loaded walk.
But the Rebels (18-6) scored on a double and two flyouts in their fourth inning, then held on.
Drew Hillman was three for four to lead the Anteaters' six-hit attack.
UCI is scheduled to begin a three-game series at Gonzaga on Friday.
WOMEN'S WATER POLO
IRVINE — No. 13-ranked UC Irvine trounced a pair of opponents in nonconference action at home Wednesday.
The Anteaters handled Maryland, 15-2, after earlier topping Cal Baptist, 17-4.
UCI (12-7) had 10 players score against Cal Baptist and nine players find the net against Maryland.
Lauren Davies had 21 combined saves in the two games for the 'Eaters.
Danielle Ward had six goals in the two games to pace the offense.
Arizona 5, UC Irvine 2
TUCSON, Ariz. — Courtney Byron won at No. 1 singles for one of few highlights for the visiting Anteaters in the nonconference match Tuesday.
Byron outlasted Sarah Landsman, 6-4, 3-6, 10-8.
Brooke Schweyer won at No. 5 singles for UCI, for which Becka Kwan and Hannah Holladay teamed to win at No. 1 doubles.
UCI is 7-9.
Arizona is 15-3.