Astros general manager Jeff Luhnow said Carlos Corporan (concussion) could return to the field later this week. Corporan took a foul ball of his facemask on Aug. 19 and has been sidelined since. Fellow backup catcher Max Stassi sustained his own concussion a few days later and is also the on the 7-day disabled list. "Corporan is further along than Stassi, and hopefully we'll get Corporan into game situations later this week, either it's with an affiliate or in Houston," Luhnow said. "We're feeling optimistic he'll be back in competition later this week. Stassi has one more hurdle left and until he clears that milestone we're in a holding pattern." Starter Jason Castro suffered a knee injury Monday, leaving Cody Clark and recently-acquired Matt Pagnozzi as the club's only healthy backstops.