On Wednesday, the Houston Astros placed starting pitcher Charlie Morton on the 10-day disabled list, citing shoulder discomfort.
The trip to the DL comes a day after Morton pitched 4.2 innings and threw 89 pitches against the Athletics on Tuesday night.
Morton joins fellow rotation-mate Lance McCullers Jr., who was placed on the DL on August 5 for right elbow discomfort.
Since McCullers' injury, the Astros initially leaned on a four-man rotation given the timing of off days in weeks after. Framber Valdez, who the Astros called up from Triple-A Fresno, won his first MLB start for Houston against the Angels on August 26.
For the season, Morton, a first-time All-Star this year, is 13-3 with an ERA of 3.14.
While the starting rotation took a hit Wednesday, the Astros got a boost for their bullpen. Setup reliever Chris Devenski was activated from the DL for left hamstring tightness. Devenski wrapped up a rehabilitation stint in Double-A Corpus Christi last week.
Entering Wednesday, the Astros were 81-51 and held 1.5-game lead on Oakland.
Here are the walk-up songs for the Houston Astros