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05/19/12 11:30 PM ET

Schafer exits after spraining ankle in outfield

HOUSTON -- Astros manager Brad Mills said Jordan Schafer will probably not play in Sunday's series finale vs. the Rangers after the center fielder sprained his inner right ankle trying to make a catch in Saturday's 6-5 victory.

Schafer underwent an X-ray, which was negative. He received treatment postgame and will have further tests on Monday to determine the extent of the injury.

Schafer was removed in the top of the third inning. He and right fielder Justin Maxwell converged on a line drive to right-center field and had to avoid a collision. Neither made the catch. The ball squeaked between Schafer and Maxwell and bounced to the outfield wall.

After limping over to the ball, Schafer threw it into the infield, but not in time to prevent the Rangers' David Murphy from scoring on a three-run inside-the-park home run. The Rangers led, 4-0, at that point.

Schafer walked off the field under his own power but couldn't put pressure on his right foot walking down the dugout stairs. Maxwell moved over to center field to take Schafer's spot and Brian Bogusevic entered in right field.

Maxwell said he and Schafer never touched one another while trying to make the catch.

"I had a pretty good beat on the ball. I just missed it," Maxwell said. "We both have good instincts out there. It was almost pretty disastrous for us, not going to lie. Hope he's OK."

Schafer was receiving treatment on the ankle and was unable to comment.

Schafer missed more than two weeks in Spring Training with a sprained wrist and has taken a beating in the regular season. He's had lower hip/back tightness and suffered dizziness when he took a knee to the head in the second week of the season.

He struck out in his only at-bat Saturday and is hitting .254 with two home runs and 11 RBIs as the Astros' regular leadoff hitter.

Maxwell hits third as Martinez moved to seventh

HOUSTON -- Astros manager Brad Mills tinkered with his lineup Saturday, giving Justin Maxwell a start in right field and putting him third in the order for the first time this season. J.D. Martinez, who has hit third for much of the season, was again dropped to seventh.

Mills said he's simply trying to take some pressure off Martinez, who entered Saturday in a 4-for-48 slump with no extra-base hits.

"I don't want to sit here and try to spin it any way that sounds good, but more than anything else I'm trying to take a little pressure of J.D. a little and see if that helps him," Mills said. "Maxwell is swinging the bat well against left-handers [lefty Derek Holland started for the Rangers] and I need somebody to hit third and I wanted to keep Jed [Lowrie] fifth."

Maxwell was hitting .350 (7-for-20) against left-handers entering Saturday, and with limited at-bats this year he knows how quickly his batting average can improve -- or suffer -- with one good day at the plate.

"It's funny when you have several at-bats and what a difference a week can make regardless of whether it's positive or negative," he said. "I'm trying not to upset my rhythm and get ready for whatever happens."

Matt Downs started at third base over Chris Johnson, who was hit by a pitch on Friday but is fine. Mills said he wanted to give Downs his first start since Tuesday in Philadelphia.

Improved plate discipline paying off for Altuve

HOUSTON -- After walking five times in 234 plate appearances last season, second baseman Jose Altuve and the Astros coaching staff focused on how he could improve his plate discipline.

It seems their emphasis has paid major dividends already.

Entering Saturday's contest against the Rangers, Altuve had 12 walks in 161 plate appearances. He has walked in 7.5 percent of plate appearances in 2012, compared with 2.1 percent in 2011.

Altuve hasn't sacrificed making solid contact to be more patient at the plate, either. His contact per swing in 2012, 92 percent, is up six percent from 2011.

"That's the type of hitter he is," Astros manager Brad Mills said. "He's good that way. He makes good consistent contact. We just want to make sure that he's being able to go deeper into counts as well."

Heading into Saturday's game, Altuve had taken 3.56 pitches per at bat in 2012. He took 3.08 pitches per at bat in 2011.

In Friday's game against the Rangers, Altuve worked three five-pitch counts against starter Neftali Feliz and walked in his second and third at-bats. That was the first multi-walk game in Altuve's career.

Astros to hold equipment drive on Sunday

HOUSTON -- The Astros will host an equipment drive before Sunday's series finale with the Rangers to benefit the Houston Parks and Recreation Department's youth baseball and softball programs.

Volunteers at Minute Maid Park entrance gates will collect new or used gloves, bats, tees, helmets, baseballs and softballs from fans as they enter the stadium. Academy Sports + Outdoors has already donated more than 200 new baseball gloves.

The Baseball Tomorrow Fund, designed to promote the growth of youth baseball and softball throughout the world, will award a $5,000 grant to the Houston Parks and Recreation Department. The grant will be given in the name of Astros outfielder J.D. Martinez, who will be recognized in a pregame ceremony for his commitment to youth baseball and softball.

The drive will run from 10:15 a.m. CT to the end of the second inning at the clock tower, right field, south home plate and Union Station atrium entrances.

Worth noting

• First baseman Carlos Lee, who's in his sixth year with the Astros, is ranked third all-time in Minute Maid Park history in batting average (.302), fourth in home runs (76) and third in RBIs (290) among players with a minimum of 200 career at-bats at the ballpark.

Brian McTaggart is reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. Clark Goble is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.