WASHINGTON -- After their 2-1 loss to the Reds on Wednesday, the Nationals recalled right-hander Blake Treinen from Triple-A Syracuse and optioned reliever Ryan Mattheus to Syracuse.
Treinen will replace left-hander Gio Gonzalez in the rotation and start Thursday's game against the Pirates. Treinen has performed well in his two stints with Washington as a starter and reliever. He is 0-1 with a 0.77 ERA in four games. The last time he pitched for the Nationals was May 6 in an 8-3 loss to the Dodgers. In that game, he pitched five innings and allowed three unearned runs.
Mattheus, meanwhile, hasn't allowed a run in 5 2/3 innings with the Nationals this season.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.