Buck, who's been out since May 29 with Achilles tendinitis, said he's ready to test his ankle in a game situation.
Buck has done basically everything he can without getting into a game. He's been taking batting practice for days and he ran the bases on Saturday.
"It's just a matter of seeing how I feel after I go play," Buck said. "I've done a lot of treatment and I can still feel it a little bit. Hopefully I'll be fine when I play and it responds well. That's the only thing I have left to go."
Buck is hitting .216 in 74 at-bats in his first year with the Astros, but he's hitting .538 (7-for-13) as a pinch-hitter, which is the best batting average in the Majors of players who have at least 10 pinch-hit at-bats. He wants to get as many at-bats as he can on his rehab assignment.
"It's a matter of seeing pitches," he said. "I want to get as many at-bats as I can because I want to come up and contribute right away. The timeframe hasn't been discussed, but I'm ready for it."