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Ross Detwiler will likely not be ready to make a rehab start this week, which would put his five days after the all-star break in jeopardy, according to Nationals Manager Davey Johnson. The Nationals expected Detwiler, who has been dealing with a lower back strain while on the disabled list, to re-join the team at the end of the rotation on July 23.

Johnson said he hasn’t been informed of any setbacks during Detwiler’s rehab. The left-handed starter, who last pitched on July 3, began throwing on Saturday. If he makes a rehab stat on Thursday, he would be on track to start for the Nationals on Tuesday. If Detwiler isn’t ready to return, rookie Taylor Jordan would be the likely bet to remain in the rotation in Detwiler’s place. Jordan, who made four starts in place of injured Detwiler and Dan Haren, has a 3.32 ERA over 21 2/3 innings.

Also, Ryan Mattheus moved his rehab assignment from a broken hand to Class AA Harrisburg on Tuesday. Mattheus began his rehab on Sunday, tossing one inning for Class A Hagerstown and allowing one run on one hit. The right-handed reliever has been out since May 19 when he broke his right hand punching a locker following a rough outing in San Diego.

“He probably needs three or four outings to make sure that there’s no problem coming back,” Johnson said.

Once Mattheus is ready to re-join the team, the Nationals will be facing difficult decisions concerning the makeup of their bullpen, which has performed well following a recent overhaul with two left-handers Fernando Abad and Ian Krol. Johnson declined to discuss the possibilities concerning the bullpen, saying it was “too early.”