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8/28/2014 8:13 P.M. ET

Grossman day to day after twisting ankle

HOUSTON -- Outfielder and leadoff hitter Robbie Grossman sat out on Thursday against the Rangers after he twisted his left ankle turning around first base following his single in the seventh inning of Wednesday's loss to the A's. Manager Bo Porter said that Grossman is day to day.

"Because [Oakland] made a pitching change, he [had time] to come in and get his ankle taped, and a lot of the time, the adrenaline helps you get through the rest of the game, but he woke up this morning and it was pretty sore," Porter said.

Meanwhile, injured outfielders Alex Presley (strained oblique) and George Springer (strained left quad) are getting closer to being activated. Presley, who's been out since July 8, hopes to take batting practice on the field on Friday. Springer, out since July 20, has been doing that for several days.

"That's the next big step," Presley said.

Both Presley and Springer went on Minor League rehab assignments earlier this month and had setbacks. Since the regular season ends for Triple-A Oklahoma City on Monday, it's unclear whether they would do more rehab if the RedHawks make the playoffs.

"We haven't talked about that yet," Porter said. "I know Presley and Springer are getting close. Are they close enough to where they can go play? We don't know that yet, but I think the more activity they're able to do and the more we're able to intensify it, that decision can be made after that."

Singleton spends extra time on picks

HOUSTON -- Third-base coach Pat Listach, who also handles the infielders, had rookie first baseman Jon Singleton on the field prior to batting practice on Thursday to work on scooping balls out of the dirt on throws, which is something Singleton has struggled with this season.

Listach threw balls from several angles, bouncing them just shy of the base, and instructed Singleton to catch them backhanded instead of forehanded.

"He's working to get his hands a little softer on the picks," Listach said. "When the ball comes and it's in the dirt, he's been picking and been going hard after balls, and I'm trying to get him to go a little softer. Make sure you see it and be soft with it and make those plays instead of being so hard."

Singleton understands he needs to clean up his defense when it came to picking balls out of the dirt. If a first baseman can't routinely make clean picks, the infielders have more pressure to make accurate throws.

"It's more about feeling than anything," Singleton said. "If you have a good feeling about it and you're seeing the ball, most likely, things are going to end up well. It's kind of a coin flip when the ball's in the dirt. The more you work at it, the better you get defensively."

Workload of Keuchel, others being monitored

HOUSTON -- Manager Bo Porter said that as the calendar flips to September, the club plans to monitor the workload of some of its pitchers, including ace lefty Dallas Keuchel. Keuchel has pitched 171 1/3 innings this season, which is just shy of the career-high 177 2/3 he threw combined in 2012 between the Major Leagues and Triple-A Oklahoma City.

"You look at his workload and the number of innings he's thrown this year, and it's something we definitely need to keep an eye on," Porter said.

The team has several starters at Oklahoma City who could come up to take some innings, a group that includes Nick Tropeano, Rudy Owens, Asher Wojciechowski and Alex White. Wojciechowski and White are coming off injuries, so that could affect whether the club sees them as viable promotion candidates.

"There are some numbers ... we're going to play close attention to, but at the same time, you watch the players, and your eyes let you know what it is you may need to do one way or another," Porter said. "We'll take all the information we have and make the best decision for each player. We'll take it case by case for each guy."

Brett Oberholtzer has also handled a larger workload this season, throwing a combined 147 2/3 innings between Triple-A and the Majors. Rookie Mike Foltynewicz has thrown only 112 1/3 innings combined, but he's being used in relief, so his workload will be easier to monitor.

Astros extend deal with Class A Lancaster

HOUSTON -- The Astros extended their player development contract with Class A Lancaster of the California League on Thursday, meaning their affiliation with the JetHawks will continue through the 2016 season. The partnership between the Astros and Lancaster began in 2009. 

"We have a wonderful partnership with the JetHawks and are very excited to extend our player development contract," Astros directory of player development Quinton McCracken said. "We look forward to fielding exciting championship players and teams in Lancaster in the upcoming years."

Lancaster has been the winningest organization in the California League for the past three seasons, posting a 233-182 (.561) combined record since 2012. The California League, specifically Lancaster, hasn't always been an easy stop for young pitchers. Mark Appel, the top pick in the 2013 First-Year Player Draft, struggled this year at Lancaster and was moved to Double-A Corpus Christi, where he has pitched better.

Earlier this week, the Astros extended their PDC at Class A Quad Cities of the Midwest League, though it appears they will have to find a new home for their Triple-A club. It was reported last week that a group affiliated with the Dodgers was going to purchase the Oklahoma City franchise and move the club's Triple-A operations there.

The JetHawks have gone 77-58 (.570) this season, and they have already qualified for a playoff spot by winning their first-half division title. Last year, the club went 82-58 and won both the first- and second-half division titles. In 2012, the JetHawks won their first California League championship.

"Coming on the heels of another season of on-field success featuring high-profile prospects, we are excited to continue our partnership with Houston," JetHawks vice president Brad Seymour said. "The Astros continue to place a lot of focus on their Minor League system, and we are thrilled that the fans in the Antelope Valley will continue to have the opportunity to enjoy watching the talent from one of the highest-rated farm systems in baseball develop on their way to the Major League level."

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