HOUSTON -- Houston Astros' All-Star closer Josh Hader was unavailable Monday night after experiencing shoulder discomfort.

Manager Joe Espada said after Houston's 7-6 win over the Red Sox that the left-hander said "he just did not feel right" after a workout Monday and they sent him for testing.

"We're waiting on those results and we should have something more tomorrow," Espada said.

Espada didn't specify which shoulder was bothering Hader.

Hader, who is in his second season in Houston, is 6-2 with a 2.05 ERA and is tied for third in the majors with 28 saves in 48 appearances this season.