PITTSBURGH -- Right-hander Jeff Karstens, who missed his last two starts due to arm soreness and fatigue, will return to the starting rotation on Sept. 19 at Arizona.

"If he wasn't feeling so much better, and the results wouldn't have been so good throwing so far, we would have shut him down," Pirates manager Clint Hurdle said. "But he was convinced he just needed a blow. We wanted see how his arm would respond. There is no discomfort and he wants to get back on the mound, and we're going to give him that opportunity. We definitely don't want to push it, but there's no red flags since we set him down, and since the fatigue he felt in the last outing when he was running out of gas."

Karstens threw a bullpen on Wednesday.

"It went really well," Karstens said. "It was nice to get back out there and try and get some of this rust off, and a couple of bullpen outings and I'll be back on the mound. Everything feels really good."

Locke to take Morton's turn against Florida

PITTSBURGH -- The Pirates will skip right-hander Charlie Morton's next scheduled start on Saturday and lefty Jeff Locke, one of the September callups, will make his Major League debut against the Marlins.

Morton lasted just 4 1/3 innings in his last outing at Chicago on Sunday, giving up four runs -- three earned -- and walking five. He hasn't made it out of the sixth inning in any of his last three starts, allowing 12 earned runs over that span.

"Locke will pitch on Saturday," Pirates manager Clint Hurdle said. "Morton, we are just going to back him off a few days, we will actually push his start back to September 14th against St. Louis, just to give him a little more time and get him a breather. The last game there was just some inconsistency, whether it was fatigue or just trying to finish really well. We'll just give him a little bit of a blow."

Locke is thrilled to be getting his first big league start.

"Absolutely, anytime you get a chance to try to make an impact in an organization, and get a big league callup and get a start, it's a big honor," Locke said. "I'm very excited and I'll tell you that Saturday can't come soon enough."

Ludwick back in lineup against Astros

PITTSBURGH -- The Pirates reinstated outfielder Ryan Ludwick from the 15-day disabled list prior to Wednesday night's series finale against the Astros.

Ludwick went on the DL, retroactive to Aug. 23, with mid-back muscle spasms. He was batting .262 (17-for-65) with one home run, three doubles and seven RBIs over 21 games since being acquired from the Padres.

"We're going to get Ludwick out there," Pirates manager Clint Hurdle said. "He's played right field in the past and we're going to leave Alex Presley in left and move Ryan to right. He's going to go out to right and we'll get his bat in the lineup. He went down and worked very hard, and we got very good reports on his at-bats and the work put in on the rehab assignment [at Indianapolis]. He's itching to go and he wants to show us he's healthy, and we want to see him healthy. He was actually starting to scratch the surface with some good things offensively before he went down."

Ludwick started in right and batted sixth on Wednesday. He went 0-for-3 with a walk in the Bucs' 7-4 victory.

"I definitely feel way better as far as being in the batter's box," Ludwick said before the game. "No one wants to go on the DL, but when you do go on the DL, I think you can try and take advantage of it, and that's what I tried to do as far as getting some rhythm and get back in the swing, and hopefully it pays off. [During the rehab], I hit the ball well, and in the two games before I went on the DL, I was really starting to feel good at the plate."

Hughes sterling in his big league debut

PITTSBURGH -- Right-hander Jared Hughes made a successful Major league debut in Wednesday night's 5-4 win over Houston, tossing 1 1/3 scoreless innings of one-hit relief.

"I thought it was a big night for Hughes," Pirates manager Clint Hurdle said. "To come in, and the first two hitters I think it was two pitches, two outs. For him to go an inning-and-a-third got us to a nice place."

Hughes, 26, posted a 3.28 ERA and a 78/36 strikeout/walk ratio in 104 1/3 innings this season between Double-A Altoona and Triple-A Indianapolis. He was called up to the Majors on Tuesday.

"I'm really excited," Hughes said. "It was a successful outing and a good win and that's the most important thing. I'm so glad we won today."

With two out and runners on first and third in the top of the fourth, Hughes replaced starter Brian Burres. The rookie got out of the jam by getting J.D. Martinez on a groundout.

"I was nervous running in, but once I got on the mound it all went away, and I was just really excited," Hughes said.

Worth noting

• First baseman Derrek Lee was 8-for-16 with two home runs and seven RBIs entering Wednesday in four games since being reinstated from the disabled list on Saturday. He hit safely in seven straight games and in eight of of his nine games overall with the Pirates since being acquired from Baltimore on Aug. 30.

• Kyle McPherson led all Pirates farmhands with 142 strikeouts, the most since Todd Redmond recorded 148 in 2006.

• Zack Von Rosenberg was named the South Atlantic League Pitcher of the Week after tossing six perfect innings in his Sept. 2 start at Delmarva.