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9/15/2013 2:59 P.M. ET

Porter welcomes chance to face playoff contenders

HOUSTON -- With the Astros set to close the season with 13 games against teams in playoff contention -- beginning Monday against the Reds -- manager Bo Porter said Sunday he wants his team to be as competitive as possible while playing in playoff-type environments.

Opposing managers would have a hard time accusing Porter of not running out his best lineup in the final two weeks, considering the Astros have been mixing and matching at several positions throughout the year.

"We want to send our best lineup out there every day," Porter said. "I think that's actually a good thing for us, and I've said this to our ballclub, that we're playing teams that are in playoff contention. I think it's good for our players to look to the other side of the field, and see the type of intensity that those teams and their fans are going to bring to the ballpark with a playoff berth hanging in the balance."

The Astros play three games against the Reds at Minute Maid Park before a seven-game road trip that features four games against the Indians in Cleveland and three against the Rangers in Arlington. The Astros close the season at home with three games against the Yankees.

One of the things Porter hopes his young team soaks up is how each player on a contending club must be a team player during a playoff push. The Astros got an example of that earlier this month, when Chris Young and Jed Lowrie of the A's both put down bunts, which certainly was out of the norm.

"When you start talking about playoff baseball, a man to a man, every player over there, they check their egos at the door," he said. "They don't care how they get it done, they don't care who drives in the runs, they don't care who moves the guys, they don't care who gets the win, who gets the save.

"The only thing they worry about is winning the baseball game, and that has to be the mindset we develop. I think it's good for our guys to actually witness that type of baseball at the stage where we are as an organization, [it] can only help us moving forward."

Castro remains sidelined with right knee soreness

HOUSTON -- It's been nearly two weeks since All-Star catcher Jason Castro has been behind the plate for the Astros because of a knee injury. He said Sunday he's making strides, but doesn't sound like a player ready for game situations.

Castro admitted last week he likely came back too soon from having a cyst drained on his right knee two days after he aggravated by fouling a ball off of it on Sept. 1. Castro started at designated hitter Sept. 6 and 7 against Oakland and went 0-for-9, and hasn't played since.

Castro hit a little bit in the batting cage Saturday and did some running, and manager Bo Porter said he's not going to play him until he's 100 percent.

"I definitely feel better than before," he said. "I think still there's a little bit of time probably left, but it's definitely making progress. From how I felt when we were in Oakland until now, it's definitely gotten better. We're kind of still evaluating and seeing what it looks like."

Asked if there was a chance he might not catch again this season, Castro wasn't sure.

"It's something I won't know until it happens," he said. "I'm not really concerned about it structurally. Everything is fine. From that aspect of it, I'm not concerned, but it's tough because it's a wait-and-see approach, and there's nothing more I can do other than listen to what it's telling me and how it feels."

Castro said that because the knee is structurally sound, he doesn't necessarily think it would put his mind at ease if he were able to catch again before the season is over. Porter, however, would like to see him behind the plate to benefit the catcher's psyche.

Stassi targets first big league action behind plate

HOUSTON -- Rookie catcher Max Stassi, who hasn't played since he suffered a concussion in his second Major League game on Aug. 21, is aiming to get behind the plate at some point this season. Stassi has been catching in the bullpen and took batting practice on the field Saturday, so he's close.

"Everything has gone well," said Stassi before catching Brad Peacock's Sunday bullpen session. "I haven't talked that over with [head athletic trainer] Nate [Lucero] or [manager] Bo [Porter] or have a timeframe. [The media's] guess is as good as mine right now."

Stassi, called up from Double-A Corpus Christi when Carlos Corporan suffered a concussion on Aug. 19, started the next two games at designated hitter, so the Astros haven't even been able to see him catch in a game situation yet.

"Hopefully we can get him clearance to at least get him in a few games before the end of the season," Porter said. "That's part of the reason we called him up when we called him up. This is valuable time. Especially if he gets some playing time and gets to catch some of [the young pitchers], it would help him going into the offseason and into next year."

Stassi has caught Erik Bedard, Jordan Lyles and Peacock in the bullpen so far.

"It was exciting to get out there and learn their stuff a little bit, even though it's only bullpens," Stassi said. "It's always the toughest thing, just not knowing the movement of their pitches. I'm enjoying it."

Worth noting

• After the Astros' top six Minor League affiliates reached the playoffs this year -- the first time that's been done since the 2003 Pirates -- the Astros wound up with two championships. Class A Quad Cities won the Midwest League on Saturday, a few days after rookie-league Tri-City won the New York-Penn League.

• Left fielder Robbie Grossman, who hasn't played since straining his oblique while swinging the bat on Sept. 3, is getting closer to returning, Porter said. The injury bothers Grossman more when he swings the bat left-handed than right-handed, but he's available to pinch-run and is increasing his activity.

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.