PHOENIX -- Needing a spot starter for Wednesday's doubleheader against the Marlins, the D-backs announced they will call up highly touted pitching prospect Tyler Skaggs to make his Major League debut in Game 1 of the day-night twin bill.

"He's had good years in the Minors, he's a big lefty and he's got strikeout stuff," D-backs manager Kirk Gibson said. "He's developed and put it all together. He's efficient and he's not afraid to let them put the ball in play, even though he can strike you out."

Gibson added he isn't sure what the club's plans are for Skaggs after Wednesday.

In nine starts at Triple-A Reno this season, Skaggs boasted a 2.91 ERA with 45 strikeouts. Before his last outing, in which he gave up eight runs, the lefty had not allowed more than one run for seven straight starts.

The 21-year-old made 13 starts with Double-A Mobile earlier this year, leaving with a 2.84 ERA and a strikeout-to-walk ratio of 3.38.

Skaggs was scheduled to start Sunday in Reno, but was a healthy scratch to make sure he could be an option for Wednesday.

The D-backs acquired Skaggs in a 2010 trade that sent Dan Haren to the Angels. The Halos originally drafted the lefty out of high school 40th overall in the 2009 First-Year Player Draft.

Along with a fastball that sits in the mid-90's, Skaggs' out pitch is his 12-to-6 curveball.

"I like the angle with his breaking ball and he's got a good fastball," Gibson said. "You want to disrupt their timing, so you want to have different pitches. You'll get away with more mistakes. He possess that trait. He's very competitive and he works hard."

National League Rookie of the Year candidate Wade Miley will start the second game of the doubleheader.

Upton contributes in first, exits with tight hamstring

PHOENIX -- D-backs outfielder Justin Upton left Tuesday's 6-5 loss to the Marlins in the first inning with a tight left hamstring, and he is listed as day to day heading into Wednesday's day-night doubleheader.

Upton injured the hamstring while running the bases after singling earlier in the five-run inning.

"When I was scoring, as I slowed down to turn to run into the dugout, my hamstring tightened up on me," Upton said. "I thought it would die down a little bit, but they advised me not to push it."

Whether the 24-year-old plays Wednesday depends on how he is doing in the morning.

"We'll see how it feels," Upton said. "I'll come in and we'll go from there."

Upton drove in two runs with his hit, and scored a run on Ryan Wheeler's sacrifice fly. Gerardo Parra took over in right field for him in the top of the second inning.

Elmore embraces opportunity at more playing time

PHOENIX -- Called up from Triple-A on Aug. 11, D-backs shortstop Jake Elmore didn't make his first Major League start until five days later when a late scratch from the lineup thrust him into the game.

But after the club shipped longtime shortstop staple Stephen Drew to the Athletics on Monday, Elmore figures to see consistent playing time in the infield, even when veteran infielder Willie Bloomquist comes off the disabled list later this week.

"I hope that's what it means, obviously," Elmore said. "If [the trade] creates more at-bats, I'm thankful, and hopefully I take advantage of them."

When Bloomquist does rejoin the team, the D-backs plan to platoon the position, starting a player on a certain day based on matchups.

"We'll probably rotate them and keep everybody fresh," D-backs manager Kirk Gibson said. "I couldn't use Willy too many days in a row, because he's not as effective. If a guy does get hot, you tend to play him more. The game will dictate how I use guys."

Back when Elmore wasn't seeing the field consistently, it made for a tough transition for the 25-year-old, who was an everyday player at Reno.

"It might've been a little bit of an adjustment, but I took it in stride," Elmore said. "I knew there were veteran players ahead of me, and they've been here a long time. I wasn't expecting to come up and start in front of them every day."

But after starting at shortstop and batting eighth on Tuesday, Elmore has appeared in six consecutive games, allowing him to get into a rhythm on the diamond.

"I'm more comfortable running out on the field," he said. "As simple as that sounds, the first couple times you go out, you can get caught up in the stadium and the jumbotron. You adapt to that fairly quick; then it's just baseball again."

In 13 at-bats entering Tuesday, Elmore has four hits, including a double.

Demel recalled to take Drew's roster spot

PHOENIX -- A day after Stephen Drew's trade to Oakland late Monday, the D-backs filled his roster spot by recalling right-handed pitcher Sam Demel from Triple-A Reno on Tuesday.

Demel was 1-4 with a 4.60 ERA in 51 relief appearances with the Aces in 2012. More recently, the 26-year-old posted a 2.79 ERA with 14 strikeouts in August.

"I've just been attacking hitters more," Demel said. "My changeup has been really good all year, so learning when to use that in certain situations was huge. I've been getting swings and misses with it. It's been good."

It's unclear how long Demel will stay with the big league club, however. The D-backs will promote top prospect Tyler Skaggs on Wednesday to start the first game of their day-night doubleheader against the Marlins, and they'll need to make a corresponding move then.

Regardless of the duration of his stint with the D-backs, Demel is just happy to be back in The Show.

"It feels good, to battle as much I did this year, to try to figure stuff out, and now I've been on a couple really good stretches," Demel said. "It's nice to be rewarded for it. It's a good feeling."

The righty held a 4.21 ERA in 34 games with the D-backs in 2011, and is 4-3 with a 4.88 ERA in 71 career games over two seasons with Arizona.

"When he left here, it was all cutter, but you have to use all your pitches," D-backs manager Kirk Gibson said. "He started off kind of rough down there, but he's thrown the ball pretty good lately."