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6/13/2013 7:06 P.M. ET

Rib-cage discomfort sidelines Marte

PITTSBURGH -- Starling Marte's hopes of building on his first career four-hit game were spoiled a couple of hours prior to the start of Thursday night's game, when he was a late scratch from the Pirates lineup due to discomfort in his left rib-cage area.

Alex Presley replaced Marte both in left field and in the leadoff spot. Officially, Marte's condition was listed by the club as day to day.

Marte went 4-for-5 in the Bucs' 12-8 victory Wednesday night, jacking his average 10 points, to .289.

It was an overall historic performance for Marte, who also scored four runs and stole two bases.

He became the first leadoff hitter for the Pirates since 1916 to put together that offensive line and the third to do it regardless of batting order position. The others were Adrian Brown on June 11, 2000, and Andrew McCutchen on May 14, 2010.

Mercer staying loose, having fun with Bucs

PITTSBURGH -- Jordy Mercer feels like a little kid again.

He's playing baseball, contributing to his team, and having fun doing it.

The Pirates dealt veteran shortstop John McDonald to the Indians for a player to be named or cash earlier this week, so it looks like Mercer is here to stay after bouncing between Triple-A Indianapolis and Pittsburgh earlier this year.

Mercer had three hits and two runs Wednesday night in the Pirates' 12-8 win, and he entered Thursday batting .278 with three homers, six RBIs and nine runs in 79 at-bats. The key to his success, he says, is just staying loose.

"You just go out and play your game, you have fun like a little kid," Mercer said. "You get all the worries and everything out."

Mercer started Thursday night against the Giants --- playing behind sinkerballer Charlie Morton, who is known for keeping middle infielders busy with ground balls. Pirates manager Clint Hurdle is confident in Mercer's defense and bat and started him against righty Matt Cain and over veteran Clint Barmes, somewhat of a defensive specialist.

"He's brought more to the table. His confidence level has never been higher," Hurdle said of Mercer. "His game has been fresh, his game is solid. So we have a lot of confidence. He's finishing games. How much more confidence can we have in a guy that's finishing games at shortstop?"

Mercer is hitting just .214 against righties this season, but Hurdle said he wants to get the Oklahoma State product in the lineup if he's going to be with the big league club. He is 10-for-23 with three homers and four RBIs against lefties this year.

Mercer is just relishing this opportunity, always with a smile on his face. And that's what playing baseball is all about to him.

"It's still a dream come true for me," he said. "It's something that you dream about as a little kid playing in the backyard. You hope to excel one day, and now that I'm getting the chance to do it, it's pretty special."

Pirates sign fourth-round Draft pick, nine others

PITTSBURGH -- The Pirates signed 10 players from the 2013 First-Year Player Draft, the team announced Thursday.

Sam Houston State lefty Cody Dickson, a fourth-round selection, was the most notable of the 10.

The Bucs also signed ninth-rounder Chad Kuhl, a righty from Delaware, and 12th-round pick Beau Wallace from Hinds (Miss.) Community College.

The club's 17th-, 18th-, and 19th-round picks -- righty Justin Topa (LIU-Brooklyn), outfielder Jeff Roy (Rhode Island) and righty Brett McKinney (Ohio State) -- also signed.

Those six will report to the Jamestown Jammers, the Pirates' Short-Season Class A affiliate.

Infielder Adam Landecker out of USC, Stetson lefty Cameron Griffin and University of San Francisco outfielder Justin Maffei, the 21st-, 23rd- and 25th-round picks, respectively, all signed and will report to the Gulf Coast League Pirates, a rookie ball team.

Infielder Michael Fransoso, the Bucs' 27th-round pick, signed and will be sent to Jamestown.

Pirates' Opening Day rotation down to Locke

PITTSBURGH -- In the thick of an escalating National League Central race, the Pirates are giving that trite baseball adage that "you can never have too much pitching" a major test.

In the middle of a weeklong homestand, the Bucs found themselves down to only one cog of their season-opening starting rotation: Jeff Locke, moved up for Friday's start against the Dodgers in place of A.J. Burnett, placed on the 15-day disabled list with a right calf strain.

Locke, the 25-year-old southpaw who missed 2013 rookie status by one inning, is also only one of two active pitchers who had any starts for the club in 2012. And that includes Charlie Morton, who only Thursday night resurfaced from a year's rehab from Tommy John surgery; 147 of last season's 162 starts are either gone or on the DL.

Yet there were the Pirates taking the Major Leagues' fourth-best record into the finale of the series against the Giants.

"It's the most depth we've ever had here," Pirates manager Clint Hurdle said. "That was part of the plan going in; I loved the rotation depth. We're in a pretty good place."

Behind Morton and Locke, the current rotation also includes left-hander Francisco Liriano, who has been very sharp since completing his recovery from a right arm fracture, and Gerrit Cole, even sharper in his Major League debut Tuesday.

Three starters on the disabled list -- Wandy Rodriguez and surprising Jeanmar Gomez in addition to Burnett -- have been among the Bucs' most dependable through the season's first two months. Another starter on the DL, James McDonald, had an All-Star caliber first half to his 2012 season and hopes remain high he can reclaim that stature.

Worth noting

• When Marte (4-for-5), Mercer (3-for-5), McCutchen (3-for-5) and Gaby Sanchez (3-for-4) went 13-for-19 Wednesday night, it marked only the fourth time in the last 59 seasons that the first four hitters in the Bucs' starting lineup each had at least three hits.

• Gomez was targeting four innings or 60 pitches in his Triple-A rehab outing Thursday night.

• Jose Tabata (oblique strain) has begun light running and throwing drills and could go on a rehab assignment in about a week.

First number, last word

.415: What the Pirates had hit with men in scoring position in the four games prior to Thursday -- compared to a Major League-low .217 before that stretch.

"Not the way that game was going. But [Russell] Martin did apologize to me." -- Jason Grilli, who was set to enter Wednesday night's game to pitch the ninth inning anyway, on whether he was disappointed that in the bottom of the eighth Martin drove in a run to make the score 12-8, removing a save possibility.

Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. Steven Petrella is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.