Melvin experiments with Dunn at first

Melvin experiments with Dunn at first

PHOENIX -- Bob Melvin told his players recently that down the stretch he would play matchups with his lineup, and he made good on his word in Monday's series opener against the Cardinals.

The addition of Adam Dunn last month along with the return of Justin Upton from the disabled list presented the D-backs skipper with a Rubik's Cube of a dilemma in terms of how to get all his hitters in the lineup at one time.

Upton, who was the team's regular right fielder before going on the disabled list July 9, had not started a game since returning Aug. 29. Until Monday, that is, when Upton was in the lineup in right and batting eighth.

To make room for Upton, Melvin shifted Dunn to first and gave Chad Tracy a day off.

"Adam has taken some ground balls at first base, he has played some first base," Melvin said. "We'll see how far we go with it. If it works, we'll stick with it. If not, obviously, we'll have to make some adjustments."

Dunn had not played first base since 2006. In his career, he's logged 100 games there.

Tracy has slumped of late, hitting just .139 with no extra-base hits in his past 10 games.

He's not the only one, though, as the offense as a whole has struggled for the better part of a week.

"We haven't been very good offensively here lately," Melvin said. "So we'll tinker with it a little bit and try to get some guys in there to mix it up a little bit and hopefully get on a roll offensively better than we have been."

Pitching matchup
ARI: RHP Yusmeiro Petit (3-3, 2.83 ERA)
Petit has been pitching like an ace the last few times out, but the right-hander hasn't pitched on a consistent basis, with several off-days for the D-backs down the stretch. Melvin has gone with a four-man rotation recently, which has given Petit starts about once every nine days or so. Petit allowed just one run on two hits in his last start against his former team, the Marlins, as he picked up his third win of the season. Petit is 2-0 with a 1.23 ERA in 7 1/3 innings against the Cardinals in his career.

STL: RHP Adam Wainwright (7-3, 3.04 ERA)
Wainwright has looked like almost the same pitcher since his return from a finger injury. In two starts since coming off the disabled list, he's allowed 12 earned runs in 12 innings, with six strikeouts, one walk and one home run allowed. The one thing he hasn't done is get a lot of swings-and-misses, but his command has been good enough that he hasn't needed them. When Wainwright starts getting fruitless swings, you'll know he's all the way back.

Tidbits
Catcher Robby Hammock and pitcher Jailen Peguero were called up from Triple-A Tucson on Monday. Hammock gives the team a third catcher while Peguero was needed due to the way the bullpen has been used recently. "We need another arm just in case," Melvin said. ... Pitchers Billy Buckner, Leo Rosales and Doug Slaten along with infielders Jamie D'Antona and Josh Whitesell and outfielder Alex Romero will join the team from Tucson on Tuesday. ... In a scheduling quirk, Monday was the first time the D-backs and Cardinals had seen each other this year. The two teams will square off for four games in St. Louis later this month. "Real odd," Melvin said. "I can't remember the last time this happened." ... Melvin was asked what it said about the organization that the two players that started on the right side of the infield Monday -- Dunn and David Eckstein -- were not with the team a month ago. "It means that we're serious about trying to fill some holes," he said.

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Up next
• Wednesday: Diamondbacks (Doug Davis, 6-8, 4.59) vs. Cardinals (Kyle Lohse, 13-6, 3.89), 12:40 p.m. MST
• Thursday: Off-day
• Friday: Diamondbacks (Dan Haren, 14-7, 3.24) at Dodgers (Derek Lowe, 11-11, 3.69), 7:05 p.m. MST

Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.