HOUSTON -- Astros second baseman Jose Altuve's return to the lineup has been pushed back to no sooner than Sunday as part of a more cautious approach to treating the hamstring injury he suffered last Sunday against Cleveland.

Altuve's injury has not worsened, but Astros manager Brad Mills does not want to put him back in without being certain that he's completely healed.

"I was probably a little too optimistic in hoping for Saturday," Mills said. "It's not a setback. We want to make sure that he's absolutely right. At the very earliest, it will probably be Sunday. We'll see how it goes today, but it might be Pittsburgh [on Monday]."

That is frustrating news for Altuve, who is more than ready to hit the field again. He currently holds the top batting average (.309) among National League second basemen while also leading in hits with 88.

Though he wants to contribute to the team, Altuve agrees with Mills in not wanting to risk an extended stay on the disabled list by returning too soon.

"I want to go out and play, but I know I have to be 100 percent," Altuve said. "Right now, I am about 80. It's funny, we've been winning games, so you want to go out and play and do things to help my team win."

Castro enjoys Harrell's gem as spectator

HOUSTON -- Taking a day off after working four games in a row for the first time in two years, Astros catcher Jason Castro got to watch one of the team's best pitched games of the year Wednesday against San Diego.

Chris Snyder was behind the plate as rookie pitcher Lucas Harrell blanked the Padres on six hits. Harrell's shutout was the first of his career.

The game time of one hour, 58 minutes -- the quickest in the Major Leagues this season -- was a dream work night for a catcher.

"To be able to catch a game under two hours is pretty rare," Castro said. "Whenever you can mix those in, that's definitely a game you want to catch, for sure."

Castro's hitting has reached a peak over the past several week. His average of .313 over the last month has raised his season mark to .255. Castro has hit safely in 11 of his last 15 games.

Not being in the lineup on Wednesday gave Castro a different perspective of Harrell's gem.

"The game is a little slower being on the side than being in the middle of it," he said. "You get to process things a little bit more and understand situations. That's why I think missing the whole year last year, I benefited from getting to watch games and I learned a lot through that process. [Wednesday] was a tremendous game thrown by Lucas and enjoyable to watch."