MIAMI -- For one more day, Patrick Corbin had to be a fan.
On Monday, the D-backs left-hander gets to be a big leaguer for the first time.
Corbin will start for the D-backs in place of Josh Collmenter in Monday's series finale with the Marlins, but because the club was holding off on making a roster move until after Sunday's game, Corbin couldn't be in the dugout.
The D-backs made that move Monday morning when they optioned right-hander Joe Martinez to Triple-A Reno. They also transferred infielder Geoff Blum from the 15-day to the 60-day disabled list.
So Corbin got to say hi to his teammates and see his uniform hanging in his locker, but he'll have to wait to put it on.
"He'll probably sit in the stands and watch the game today, and tomorrow's show time," D-backs manager Kirk Gibson said. "It's a very exciting time whenever you're making your Major League debut. It's what you dream about, it's what you work hard for. It's what you earn, you earn the opportunity."
Corbin got the opportunity thanks to a strong Spring Training and a 1.67 ERA through his first four starts at Double-A Mobile.
Collmenter, 0-2 with a 9.82 ERA in four stars, will be moved to the bullpen.
First base a balancing act for Gibson
MIAMI -- First base has become a difficult juggling act for D-backs manager Kirk Gibson.
On the one hand, Paul Goldschmidt is viewed as the future at the position, given his performance in 2011. However, it's been a tough start to the season for the slugging right-hander, while backup Lyle Overbay has been swinging a hot bat.
"You want to show confidence in them and play them, but at the same time, you want to keep everybody playing," Gibson said of his lineup decisions in general. "There's times I think that you want to try to balance it, give a guy some time to relax and work on some things."
Overbay, who is hitting .308 with a .919 OPS (on-base plus slugging) got the start in the first game of the series against the Marlins on Friday, and Goldschmidt, who is hitting .185 with a .540 OPS, started Saturday. On Sunday, Gibson once again went with Overbay.
"He's done well," Gibson said of Overbay. "Goldy, actually, I think he's coming around a little bit. He's starting to swing the bat a little better. I've watched him in the cage a little bit."
Overbay credited some mechanical adjustments at the plate for his improved results. He has also tried to help Goldschmidt get going.
"Goldy will figure it out and be all right," Overbay said. "When you start struggling a little bit, then you start looking for answers. Hopefully he knows that I'm there for him. He's going to be a big part of this."
Vlad to work out for D-backs in Dominican
MIAMI -- Free-agent outfielder Vladimir Guerrero will work out for D-backs general manager Kevin Towers this week in the Dominican Republic.
Guerrero, 37, hit 449 home runs over 16 years in the big leagues. Last season, Guerrero hit .290 with 13 homers and 63 RBIs for the Orioles.
Towers is headed to the Dominican to see some amateur players, and D-backs vice president of Latin operations, Junior Noboa, suggested Towers take a look at Guerrero.
"Junior knows him and likes him and says he looks good," Towers said. "Who knows what comes of it. He's out there. Junior knows him well and he's in the Dominican. He said he's in good shape. I'm going to be down there for a workout anyway."
Towers was asked if Guerrero would be a fit as a designated hitter for Arizona's Interleague Play games much like Wily Mo Pena was last year.
"I'll have a little better idea depending on what I see," Towers said.
Zagurski hoping to stick around after Reno stint
MIAMI -- It didn't work out quite the way he expected, but Mike Zagurski is happy to be in the big leagues.
The D-backs left-hander, who was out of Minor League options, had an impressive spring, and it was widely assumed if he did not make the team, he would be claimed on waivers by another team before he could be sent to the Minors.
Zagurski, however, did clear waivers and began the season for Triple-A Reno.
"It just didn't work out at the time, but I went down there for a couple weeks and was fortunate enough to get back and hopefully will be here for a long time," Zagurski said.
Rather than pout about his situation, Zagurski continued to pitch well, compiling a 2.00 ERA in six games for Reno before being called up to replace left-hander Joe Paterson last week.
In his lone outing heading into Sunday, Zagurski allowed one run -- a homer -- in two innings.
"I think it's a constant battle to try and get better every day," Zagurski said. "I thought I had a pretty decent spring, and going down to Reno, I felt like I threw the ball even better in Reno than I did during the spring. I felt OK about my outing the other day. One bad pitch. I didn't execute great, but I got through it for the most part and it's something to build on."
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.