The Washington Nationals placed starting pitcher Doug Fister on the disabled list Saturday because of a strained muscle in his back.

“There’s no rhyme or reason for any of it,” Fister said. He said the lat discomfort was a “total surprise.”

The 30-year old right hander will be shut down for five days before beginning rehabilitation and is expected to miss anywhere from three to four weeks, according to manager Matt Williams. Fister already missed time during spring training because of inflammation in his pitching elbow. However, his latest injury is not believed to be related.

“It’s more precaution than anything,” Williams said. “I don’t think it had anything to do with the elbow. The elbow has been fine thus far since he first had the inflammation.”

He was traded to the Nationals this off-season from the Detroit Tigers in exchange for utility player Steve Lombardozzi and left handed pitchers Ian Krol and Robbie Ray. Last season, Fister went 14-9 with a 3.67 ERA in 32 starts and 208 innings pitched.

Taylor Jordan will take over as the Nationals fifth starter while Fister rehabs. The team will open the season with Steven Strasburg, Gio Gonzalez, Jordan Zimmermann, Taylor Jordan and Tanner Roark in their rotation. Roark will start in Washington’s home opener Friday against the Braves.