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Ross Detwiler may not pitch again this season, according to Manager Davey Johnson. Detwiler has been out since July 4 with a herniated disk in his lower back. He has been playing catch and recently resumed running. He was doing resistance running Tuesday afternoon on the outfield of Nationals Park.

But still, Johnson said. Detwiler’s status is uncertain. The left-handed starter may be running out of time in order to get back on the field. According to Johnson, Detwiler would perhaps have to be on an accelerated throwing program to return before the season is over. That would only happen if Detwiler had no setbacks.

The Nationals have vacillated in their belief if Detwiler will return this season, saying that he likely wouldn’t and then saying that they hope he does. Asked on Tuesday if he felt Detwiler would return this season, Johnson wasn’t hopeful.

“Probably not,” he said. “He’s been out so long. It’d be nice to see him throwing at full speed before the end of the year. Whether or not we take a chance on pitching him I don’t know. That’s going to be strictly for the doctors.”

>>> The Nationals recalled right-handed reliever Ryan Mattheus from Class AAA Syracuse before Tuesday’s game and optioned left-hander Xavier Cedeno. The Nationals called up Cedeno from Syracuse Friday after the trade of David DeJesus, but he didn’t appear in a game yet again. He had been called up several times this season but has appeared in only two games.

Mattheus returns after five appearances with Syracuse. He allowed only one earned run, struck out three and walked none during those 5 1/3 innings. Mattheus was optioned to Syracuse two weeks ago to iron out issues that had contributed to the worst season of his young career. He posted a 6.26 ERA over 23 innings and still struggled when he returned from a broken right hand on Juy 26.

>>> Bryce Harper received an X-ray following Sunday’s game and the results were negative, Johnson said. Harper fouled a ball off his left foot and still managed to single in the at-bat and homer in the next one.

>>> Jayson Werth’s foot infection, which held him out of Saturday’s game, has completely improved, Johnson said. Werth was set to be examined by team doctor Wiemi Douoguih on Tuesday. “It looks 100 percent better than it did a couple days ago,” Johnson said.