The Washington Nationals have placed starting pitcher Ross Detwiler on the 15-day disabled list with back discomfort and will activate Dan Haren to start on Monday in his place, manager Davey Johnson announced, via Adam Kilgore of the Washington Post.
Detwiler felt stiffness in his lower back earlier on Saturday while throwing a side bullpen session. Johnson had said earlier the southpaw was "questionable" to make his next start and that "nothing needs to be done at this time," but that situation apparently changed.
The starter missed a month earlier this season with a strained right oblique. Detwiler went 2-3 with a 6.31 ERA in five starts since his return.
The Nationals had planned for Haren to return on Tuesday. Haren threw a simulated game on Wednesday, so his schedule does fit for him to start on Monday.
Washington placed Haren on the disabled list June 23 with right shoulder inflammation. Haren has struggled for the Nationals this season, going 4-9 with a 6.15 ERA.