The Houston Astros are now in a fight to remain on top of the AL West standings.

After it once looked like they were going to run away with things despite all the injuries they have suffered, the Seattle Mariners have gotten red-hot in the month of August and chased them down to put the gap at just 1.5 games entering Friday’s action.

With the margin between the two contenders so tight, the Astros need to find a way to overcome their latest bit of adversity with Josh Hader going on the injured list for the first time in his career with a shoulder injury.

The good news is that the update provided suggests the superstar closer has a chance to return at some point during the regular season, with him being shut down from throwing for the next few weeks where he’ll be assessed after that.

While that’s a major blow to a bullpen unit that has been one of the best in the sport throughout the year, they also have plenty of high-end arms capable of filling in during that time to keep Houston on pace to win the division.

Unfortunately, before they got their three-game series started against the Baltimore Orioles, the Astros were dealt another bit of adversity with one of their best players being forced to miss the contest.

Starting shortstop Jeremy Pena reportedly showed up to the ballpark before Friday’s contest and met with team doctors, but ultimately he was given the day off because he felt under the weather, according to manager Joe Espada.

“We want to make sure that he’s good to go and also that it’s not something that could get the rest of the guys sick or anything like that, so we’re getting some tests done,” he said, Matt Kawahara of The Houston Chronicle (subscription required).

Pena was in the midst of his career-best season before he hit the injured list on June 30 with a rib fracture on his left side. He’s been solid since he returned on Aug. 1 with a season-long slash line of .318/.373/.492 to go along with 13 home runs and 45 RBI.

With Pena out, Mauricio Dubon will take over at shortstop and bat eighth in the lineup with the aim of getting this series started right as the Mariners take on the New York Mets in a weekend set.