HOUSTON -- Nelson Figueroa was one of the biggest feel-good stories of Spring Training when, as the oldest player on the club, he made his first Opening Day roster and finally had a guaranteed contract and a spot in the starting rotation.

Less than six weeks into the regular season, Figueroa finds himself once again in career limbo after the Astros designated him for assignment following Monday's 6-1 loss to the Reds. The Astros have 10 days to trade, release or reassign him to the Minor Leagues. The Astros recalled left-hander Sergio Escalona from Triple-A Oklahoma City.

Figueroa, 36, was claimed off waivers by the Astros last July and went 5-3 with a 3.22 ERA in 18 games, including 10 starts, for the Astros. He struggled in the rotation this year in five starts and was 0-3 with an 8.69 ERA in eight appearances overall.

"Any time a guy does what he did for us last year, he was able to really stabilize that rotation for us last year and threw the ball extremely well," Astros manager Brad Mills said. "Hopefully, there's some way he can get it back. I don't know exactly what's going to happen with him. That will be his decision."

Figueroa, who allowed one run on three hits, two walks and three strikeouts over two innings on Monday, declined to comment on his future.

Escalona, who will be the first Astros player since Roy Oswalt to wear No. 44, was acquired from the Phillies in a trade for a Minor League player in January. He was 1-0 with a 3.38 ERA and three saves in 13 relief appearances at Oklahoma City and will join the club Tuesday, giving Mills two lefties in the bullpen, joining Fernando Abad.

"He's been throwing the ball really well at Okie City," Mills said. "The benefit of having two lefties in the bullpen is going to be important."

Closer role undefined for immediate future

HOUSTON -- When it comes to identifying a closer with Brandon Lyon on the disabled list, Astros manager Brad Mills is taking it day by day.

Mills said right-hander Mark Melancon would serve as the closer for Monday's series opener against the Reds, but he's not ready to say Melancon's the closer in the short term. Mills said determining which pitcher closes games will have more to do with matchups and situations.

"We're still kind of going through a process," Mills said. "We can call Melancon the closer tonight and go from there. I'm not trying to dodge the question, but we might have to mix some things around and depending on what part of the lineup we're with and so on and so forth. There's no reason to think we're not going to be able to get some outs before we get to Mark either."

Houston began play Monday with a bullpen ranked 30th in the Majors with a 5.54 ERA and a .305 batting average against. The Astros had converted only five of 14 save chances for a league-low save percentage of 35.7. Melancon recorded his first Major League save Friday.

Mills has confidence the bullpen will rebound and said the best way to accomplish that is to keep running the arms back to the mound.

"We're in a period where sometimes you have to get through it and maybe bite the bullet a little bit, and you might wind up losing a few of those games, but at the same time, that experience is going to get it," Mills said. "When they're able to experience other relievers going out there in situations -- whether on your team or another team -- and see how they go about things and pitch selection and mannerisms and mound presence and things of that nature ... and going through the experience themselves, [that's key]."

Towles moves up to No. 2 in lineup

HOUSTON -- J.R. Towles knew he was going to start Monday's game against the Reds, so when he came to the ballpark, he immediately glanced at the No. 8 spot in the lineup card. Not seeing his name, he looked up a spot to No. 7. Still no Towles.

"I looked up even more and I was in the two-hole," the Astros catcher said. "I'm excited about that. I hit at the top of the order in the Minor Leagues a lot, and I even hit in the two-hole and leadoff several times."

Towles hit second in the batting order for the first time in his Major League career on Monday, a spot that's extremely favorable in the Astros lineup. With Michael Bourn leading off, pitchers tend to throw mostly fastballs to the next hitter, if Bourn gets on base in an effort to keep him from stealing. Plus, Hunter Pence is batting third.

As manager Brad Mills explained, having Towles hit second, Pence third and Carlos Lee fourth enables him to put the solid bat of Brett Wallace lower in the lineup and make the bottom of the order a little more challenging for pitchers.

But he was looking forward to seeing what Towles could do batting second.

"I thought it would be a good spot for [Towles] to be able to hit behind the runner, move runners," Mills said. "He's a good fastball hitter and hopefully, he'll get some more fastballs with Michael Bourn getting on. All those things will be big."

Towles went 0-for-4 in the Astros' 6-1 loss to the Reds.

Keppinger nearing start of rehab assignment

HOUSTON -- Jeff Keppinger appears to be close to taking a big step forward in his rehabilitation from offseason foot surgery.

Astros manager Brad Mills said Monday the versatile infielder could begin a Minor League rehab assignment as early as Thursday. Keppinger, who underwent surgery in January to remove a bone from his foot, has been alternating between designated hitter and the infield for the last few weeks at extended spring training.

"We're going to see how he is today and tomorrow and go from there," Mills said. "If there's no soreness and he feels OK, he could start as early as maybe Thursday."

Keppinger, who can play shortstop and second base, was one of the Astros' most reliable players last year, hitting .288 with a team-best 34 doubles and six homers and 59 RBIs in 137 games. His return will give Mills an intriguing decision to make regarding which infielders stay on the roster.

Worth noting

The Astros will reassess outfielder Jason Michaels following Wednesday's game. Michaels, who's on the disabled list with a left shoulder subluxation, went 2-for-5 on Monday at Triple-A Oklahoma City and is 3-for-12 in three games during his rehab assignment.