JOSH FIELDS/Arizona Daily Wildcat Junior first baseman Jordan Brown throws out an ASU player at first base Wednesday night at Sancett Stadium. The No. 9 Wildcats take on UC Riverside today at 4 p.m. at home, followed by games Saturday and Sunday.

A year ago, Sean Rierson was just like any other college student - working at a restaurant to make money to pay for college.

Now he's making his bid for a starting spot in the No. 9 Arizona baseball team's starting rotation.

The fifth-year senior, who spent last year as a medical redshirt while recovering from Tommy John surgery, makes his first start of the season Sunday when the Wildcats (10-1) host UC Riverside (5-6) for a three-game series at Sancet Stadium.

The teams play Friday at 4 p.m. and Saturday at 1 p.m. before Rierson's Sunday start at noon.

It's been a long way back for Rierson (1-0, 4.50 ERA), who spent the 2003 season as the Friday starter at Arizona and has not started since May 2003.

Now he pays his own way after forfeiting his scholarship last year, as the Wildcats weren't sure if he would ever return.

"It's good to be back in the starting rotation," Rierson said. "It's another step in the progress of getting back to 100 percent healthwise."

Arizona head coach Andy Lopez said he hopes to get four or five innings out of Rierson and will probably pull him around the 70-pitch mark, as Rierson builds back arm strength.

Rierson will take the place of the typical Sunday starter, freshman David Coulon, who threw four innings in Wednesday's 11-5 win over ASU.

Rierson adds a veteran presence to a pitching staff that has relied on freshmen for four starts this season.

"He pitched for three years and averaged eight, nine wins a year," Lopez said. "He's pitched in the regionals, so he has a lot of experience. We want to give him every opportunity to get back to where he was, and that's basically what we're doing. We're going to give him a chance to get back to where he was."

Rierson impressed in first two outings of the year, but turned in a disappointing appearance his last time out.

He did not allow a hit for a three-inning save in the team's 13-2 victory over Northern Colorado Feb. 12, but gave up four runs in 2 2/3 innings of Sunday's loss to Texas Pan-American.

"The first two outings definitely gave me confidence," he said. "The third one I was a little bit discouraged about, but I'll put that behind me, learn from it and go on."

Rierson said he feels fully healthy, but that he possesses only 80 to 85 percent of his endurance.

"I have no pain or anything like that, but I definitely get to a point where I hit a wall and just start to break down," he said.

As has been the case the rest of the season, the rotation will consist of juniors John Meloan (2-0, 0.54) starting Friday and Kevin Guyette (2-0, 3.06) getting the nod Saturday.

They will battle a Highlander team led offensively by catcher Nick Salotti (.333, three home runs, 11 RBIs) and Aaron Grant (.353, one home run, 11 RBIs), but that bats only .233 as a team.

The hot Arizona offense will take on a Riverside rotation with a 5.31 ERA, including likely starters Taylor Bills (2-1, 4.38), Haley Winter (1-2, 1.84) and James Simmons (1-1, 3.86).

Arizona averages 11 runs per game and has reached double digits in hits in all but one game.

"When you're scoring runs it makes everything a little bit easier (and) less stressful," Lopez said. "Again, it's not realistic to think you're going to hit .378 the whole year, but as long as we get timely hits, it's OK."

The Wildcats also must avoid a letdown two days after beating rival ASU for the second week in a row in an emotional game.

"You don't want to come out too high or too low after a big win," said junior first baseman Jordan Brown. "Basically, we want to come out and do the same things we did against Arizona State: play well, play hard and play under control."

The biggest boost Arizona could gain this weekend involves Rierson's continued rehabilitation.

If he can return to full strength for the Pacific 10 Conference season, Arizona could add a valuable arm to its rotation.

"As a starter before, it just used to be that I can get us six, seven innings," Rierson said. "It brings my experience that I've had over the three years and just being a Friday guy before.

"Now being in the Sunday spot, it's going to say, 'Hey, (I'm) back as far as the arm goes.' Now I'm going to start pushing the Saturday and Sunday guys to keep them on their toes."