PHILADELPHIA -- Astros pitcher Brian Moehler, who's been on the disabled list since July 8 with a groin injury, will be out for the rest of the season after deciding Wednesday to undergo surgery to repair a muscle in his lower abdomen. The surgery will be performed Sept. 1 in Philadelphia by Dr. William Meyers.

Moehler was forced to leave his Minor League rehab start Tuesday night at Triple-A Round Rock after three innings when he felt discomfort in the groin area. Moehler tore the tendon off a bone in his groin while throwing a simulated game three weeks ago in St. Louis and opted at the time not to undergo surgery and try to rehab the injury.

"It just hasn't responded like I had hoped," Moehler said. "I was getting some sharp pain when I threw breaking pitches and sinking fastballs, and in the third inning last night it got to the point when they'd call a pitch and I'd say, 'What's this going to feel like when I throw it?' It wasn't going to work without surgery."

Moehler, 38, went 1-4 with a 4.92 ERA in 20 games, including eight starts for the Astros this year. He's a 14-year veteran who's 84-107 with a 4.81 ERA in 332 career games, including 252 starts. This is his fifth season with the Astros (2003, 2007-10).

"I'd like to play next year, but we'll see what happens," Moehler said. "It's better off to get the surgery done now than later and it gives me the opportunity, if there is an opportunity to play next year, to get ready and come to Spring Training. It's not a major surgery. I'll be able to pitch again, so it's not a big issue. The longer I waited, the longer it would take me to get back and throw."

Moehler plans to stay in Houston to rehab for the rest of the season. He could begin a throwing program as soon as November if all goes well.

Sore neck sends Blum home for examine

PHILADELPHIA -- Veteran infielder Geoff Blum flew home to Houston on Wednesday and is scheduled to have his sore neck examined by Dr. Michael McCann on Thursday morning. He's the same doctor that helped Roy Oswalt navigate through his back issues the last few years.

Blum has been available on a limited basis since injuring his neck while diving to catch a ball behind second base last week against the Mets in Houston. Blum had been starting at second base with Jeff Keppinger on the disabled list.

"He was feeling much better last night after the game and we asked him if he would be able to play today, and he said yes, he wanted to be in the lineup," manager Brad Mills said. "He got here real early and said, 'Millsie, it's worse today than it was yesterday and I can hardly move.' And so we kind of talked a little bit and he went in to get some treatment.

"We talked to [general manager] Ed [Wade] and [head athletic trainer] Nate [Lucero] and decided we have to get some answers because it's been a while now. We decided to send him back to see Dr. McCann. He has an appointment in the morning with him and hopefully we'll know something by the end of our game tomorrow afternoon at the latest."

Blum is hitting .262 with one homer and 17 RBIs. He underwent elbow surgery July 7 and missed 25 games while on the disabled list.

Astros add infield depth by claiming Downs

PHILADELPHIA -- The Astros claimed infielder Matt Downs off waivers from San Francisco and assigned him to Triple-A Round Rock, where he will report Thursday. Downs, 26, was designated for assignment Sunday after playing in 29 games for the Giants and hitting .244.

"Our reports on him were that he's a multi-position guy, possibly and everyday guy at second," Astros general manager Ed Wade said. "He's just a good baseball player who gets the most out of his ability, one of those types of guys. He has options remaining and buys a little bit more depth. We had a roster spot available, and so it made sense to claim him."

Downs started 18 games for the Giants this season, all coming at second base. He's spent his last two months in the Giants' Minor League system and has combined to hit .255 (52-for-204) with seven homers and 30 RBIs in 58 games with Triple-A Fresno and the rookie Arizona League Giants. He's spent parts of two Major League seasons with San Francisco (2009-10) and owns a career .300 Minor League average since being drafted in 2006.

Wade said the Astros made the decision to claim Downs before veteran infielder Geoff Blum was sent to Houston on Wednesday to have his ailing neck checked out. Downs could find his way to Houston when the rosters expand next week because starting second baseman Jeff Keppinger is on the disabled list, but the Astros also have Oswaldo Navarro, Edwin Maysonet and Matt Kata available as second base options at Round Rock.

Lindstrom throws from the mound

PHILADELPHIA -- Matt Lindstrom, who's been on the disabled list since Aug. 16 with a lower back strain, threw 35 pitches in the bullpen prior to Wednesday's game without incident. It was the first time he had thrown off a mound since landing on the DL.

"It went good," Lindstrom said. "Considering the fact I haven't been on the mound for a week or whatever it's been, throwing without reservation is a nice feeling. I actually got to run center field sprints today. That's part of my conditioning.

"I haven't been able to do that because of the layoff I've had. I just need to continue to get a feel out on the mound and be ready to go when this stint on the DL is over. I'm pretty optimistic where I'm at now, especially considering I have five or six more days [left on the DL]."

Lindstrom is 2-4 with a 22 saves in 28 chances this year and a 4.15 ERA. He's been dealing with back issues for several weeks, but hopes having some time off the mound has helped him past his problems. He will throw another bullpen session Friday in New York.

"It's kind of nice going out there and stretching it out for 30, 35 pitches," he said. "I felt strong and obviously I'm progressing. I felt good."

No roster moves needed in wake of marathon game

PHILADELPHIA -- Astros manager Brad Mills and general manager Ed Wade met briefly following Tuesday's 16-inning win over the Phillies to determine if the club needed to make any roster moves to replenish the roster in time for Wednesday's game.

The Astros used 21 players in the game and saw relievers Fernando Abad, Mark Melancon and Jeff Fulchino throw multiple innings. Mills and Wade were also concerned about the availability of catcher Jason Castro, who got hit with a ball on the knee late in the game and was forced to stay in the game because the club was out of catchers.

"I think there will start to be some concern if we start getting up in numbers of extra innings, but I think we have some guys who will give us an inning or two out of the 'pen," Mills said.

Mills said he was going to try to avoid using Castro on Wednesday, but was hoping reliever Brandon Lyon would be ready to go. Lyon has endured a heavy workload the last couple of weeks and is taking longer to recover between outings.

J.A. Happ, who started Wednesday's game, went to the bullpen in the 15th inning Tuesday and would have followed Fulchino to the mound had he not been able to close out the game. Mills admitted first baseman Brett Wallace likely would have had to assume the catching duties had Castro not been able to continue Tuesday.

Adrenaline was flowing for Oswalt

PHILADELPHIA -- Roy Oswalt got his chance to play against the Astros, his former team, but it wasn't in the fashion he could have envisioned. After being inserted into Tuesday's game in the 15th inning as a left fielder, he admitted his adrenaline was flowing.

"I probably hadn't had that much adrenaline since the first day I got called up," Oswalt said. "I've played 10 years in the big leagues and I go to the mound every time. It's different for sure. It's a whole different feeling."

Oswalt, traded from the Astros to the Phillies last month, held his own in the outfield, catching a soft fly ball off the bat of former battery mate Jason Castro. No other balls were hit his way, but he was prepared to throw out a runner at the plate.

"Oh, no doubt," Oswalt said. "Shane [Victorino] actually walked over there and said, 'If there's a high fly ball do you want me to catch it and throw it?' I said, 'No.' That's what I've been wanting to do forever is throw somebody out at the plate."

Worth noting

Astros' second-round pick Vincent Velasquez, a right-handed pitcher, is scheduled to see team physician Dr. Tom Mehlhoff on Monday after leaving Tuesday's game with an elbow injury. ... Third-round pick Austin Wates, an outfielder, left Tuesday's game when he was hit on the right hand by a pitch, but X-rays were negative. He's day-to-day.