In February, Detwiler had surgery to repair a labral tear in his right hip. He missed all of Spring Training and has yet to play in a game. Detwiler said he should know by the end of the week when he will start his rehab assignment.
Detwiler said there is no timetable as to when he will return to the big leagues.
"This is like my Spring Training now, so I could build up arm strength before I leave here," Detwiler said by phone. "The team is trying to figure out a schedule for me. They have to finalize that, and we'll go from there."
Detwiler said he realizes that he must produce once he starts pitching in a Minor League rehab assignment. He realizes the Nationals have a handful of pitchers -- Stephen Strasburg, Chien-Ming Wang and Jordan Zimmermann -- who are expected to be in the big leagues soon.
"There is not going to be a job waiting for me," Detwiler said. "Even when I go to my rehab assignment, I still have to perform."
Last season, Detwiler went 1-6 with a 5.00 ERA in 15 games with Washington, but had a 1.90 ERA during the month of September.