The Washington Nationals activated pitcher Ross Detwiler from the 15-day disabled list to start Thursday's game in Colorado.
Detwiler had been sidelined because of a muscle strain in the right side of his back.
The lefty originally sustained tightness in his lower back on May 15. Detwiler, who was also dealing with a right oblique strain, entered the day 2-4 with a 2.76 ERA over eight starts this season.
To make room on the roster, Washington optioned pitcher Erik Davis to Triple-A Syracuse.