Josh Slaats' first start at the top of the Hawaii rotation has been put on hold.

The 6-foot-5 junior right-hander will miss his scheduled start tonight when the Rainbows (6-6) begin a four-game series against Southern California (6-7) at Les Murakami Stadium.

Slaats, who has been nearly unhittable in three starts this season, complained of soreness in his elbow after throwing a bullpen session on Wednesday.

The reigning Western Athletic Conference pitcher of the week is 1-0 with an 0.52 ERA after tossing a seven-inning, two-hit shutout against The Citadel last weekend.

“;It's so early (in the season) that we're going to go ahead and hold him out,”; Hawaii coach Mike Trapasso said. “;If it were a conference game or later in the season, he'd go out there.

“;He was checked out by the doctor and the doctor said he's fine and he could go, so we'll either skip him a start or he could possibly go on Monday.”;

As a result, the rotation will be moved up a day, with former Trojans pitcher Nate Klein (1-0, 5.60 ERA) starting tonight. Lefty Sam Spangler (1-2, 2.93) will get the nod tomorrow and sophomore Matt Sisto (1-2, 7.13) will go on Sunday.

If Slaats isn't able to throw Monday, the Rainbows will use whoever is freshest out of the bullpen after the first three games.

It opens the door for Klein, who spent two seasons at Southern California, to get his first crack at his former team tonight. The senior right-hander transferred out of USC after coming back from Tommy John surgery in 2007.

“;He always runs into trouble when he tries to do too much,”; Trapasso said. “;It'll be key for him to get past the emotions of playing his former team and just settling down and pitch the way he's used to pitching.”;

This series will test the Trojans' mental and physical toughness. USC shut out Pepperdine on Tuesday and lost to Connecticut on Wednesday night before turning around and catching an 8 a.m. flight to Honolulu yesterday morning.

The Trojans got in an evening practice at Les Murakami Stadium last night and will complete a stretch of eight games in nine days when the series wraps up on Monday.

USC has been searching for consistency this season after losing three players in the first two rounds of the Major League Baseball First-Year Player Draft last summer.

Sophomore Andrew Triggs, who will start for USC tonight, is rated the No. 38 overall prospect by Baseball America. The 6-foot-3 right-hander is 1-0 with a 4.12 ERA in three starts and averages a strikeout per inning pitched.

“;Everything I've heard about him says he's the real deal,”; Trapasso said.

Like Klein, Triggs had Tommy John surgery on his right elbow. After missing his senior year of high school and sitting out two years, he was one of the biggest surprises for the Trojans last year, compiling a 5-3 record with a 3.96 ERA.

Triggs isn't the only highly rated Trojans player. First baseman Ricky Oropesa (.262, 3 HRs, 8 RBIs) is rated the No. 23 overall college sophomore (Triggs is No. 28).

“;They're capable of putting up a lot of runs,”; Trapasso said. “;They've been inconsistent this early part of the season ... but they're big and strong and physical and they'll have guys who go out and struggle and then the next game come out and score 10 runs.”;

USC, which is the third of four Pac-10 teams the Rainbows will play this season, was picked to finish eighth in the Pac-10 in the preseason coaches poll. Oregon State was picked to finish second and Oregon was 10th. Hawaii also plays a single game against Stanford, which was picked to finish fourth.