HOUSTON -- Tommy Manzella knew right away something was wrong after diving for a Bengie Molina one-hopper in the sixth inning Tuesday and jamming his left index finger into the ground. He stayed in the game and got out of bed Wednesday hoping for the best.

"It was too swollen to the point I couldn't really bend it at all," Manzella said.

Manzella was examined by team physician Tom Mehlhoff and then sent for X-rays, which revealed a fractured finger. Manzella, the Astros' starting shortstop, is expected to miss at least six weeks and was placed on the 15-day disabled list. Houston recalled shortstop Oswaldo Navarro from Triple-A Round Rock.

"It's very frustrating, but it's part of the game," Manzella said. "It's kind of new for me. I've never really had to deal with injury before. When I pulled my quad in Spring Training that was new for me, and I didn't know how to handle that. I thought that was going to be my frustration for the year, but this is another obstacle I have to overcome."

Manzella's index finger, which was outside his glove, got caught in the grass as he rolled over his hand with the ball in his glove. He remained in the game until being replaced by a pinch-hitter in the ninth inning.

The injury comes at a bad time for Manzella, who was beginning to make progress at the plate. The rookie was hitting .212 with homer and 16 RBIs in 56 starts, but he was hitting .285 with eight RBIs and four multihit games in his last 12 games before being injured.

"I'm starting to get to that 200 at-bat area in the big leagues and starting to figure out the adjustments I have to make and starting to see the adjustments from the work I've put in all year," he said. "In that respect, it's a little frustrating, but part of the game is being able to mentally bounce back from adversity, whether on the field and statistically oriented or win-loss oriented or whatever."

Geoff Blum started at shortstop Wednesday, but manager Brad Mills said he didn't want to use the veteran too much at the position. That means Blum and Navarro will split time.

"Right now I'm not really sure how many games straight that Blummer can play, to tell you the truth," Mills said. "It's a position he hasn't played in a few years. He's played it periodically. I'm not concerned about how he's going to play, but I'm concerned about the toll it might take on him more than anything else, like anyone who hasn't played there for a while.

"Navarro has played quite a bit in Round Rock. It's nothing against Blummer at all. It's just how many days he's going to be able to play. He's done a very good job playing there the few times he's been out there already."

Blum, hitting .226 with no home runs, made his 26th start of the season Wednesday, including sixth at shortstop. He's hitting .286 with a triple and seven RBIs as a pinch-hitter this year, ranking second in the Majors in pinch-hit RBIs.

"It's definitely going to affect the bench, there's no doubt," Mills said. "He and Jason Michaels have been stalwarts for us off the bench and done such a good job. But again, depending on how much he plays and starts out there and with Navarro, we'll have to see how it goes."