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8/27/2013 7:35 P.M. ET

Nationals recall Mattheus, option Cedeno

WASHINGTON -- The Nationals recalled right-handed pitcher Ryan Mattheus from Triple-A Syracuse and optioned left-hander Xavier Cedeno to Syracuse.

Mattheus is 0-1 with five holds and a 6.26 ERA in 23 games with Washington this season. He allowed just one earned run with three strikeouts in 5 1/3 innings during his five appearances with Syracuse.

Cedeno has not allowed a run in two relief appearances (1 1/3 innings pitched) with Washington. He is 0-0 with a 9.39 ERA in seven relief appearances this season with the Nationals and Houston Astros.

Nats weighing whether to call up Espinosa

WASHINGTON -- The Nationals have not decided if they will call up second baseman Danny Espinosa on Sunday, when rosters can expand. A baseball source familiar with Espinosa believes he will not play another big league game this year.

The person pointed out that Espinosa has 96 strikeouts in 287 at-bats for Triple-A Syracuse. Those numbers don't help the Nationals, who are trying to trade Espinosa, according to the source. Espinosa also has a .208 batting average for Syracuse entering Tuesday's action.

Espinosa's agent, Scott Boras, acknowledged that the infielder has to refine his approach at the plate.

"The Danny that we all know has the Major League tools to play shortstop and second base in the big leagues," Boras said. "Every park that I go into will ask me about Danny. They want to know what he is doing. So the guy has real value. The thing he has to go through is get an approach that will help him become very consistent [at the plate]."

In Espinosa's defense, he has been dealing with injuries dating back to last September. First, he had a torn rotator cuff, which hampered him during the National League Division Series against the Cardinals. Then he had right wrist problems, which put him on the disabled list this June. He was optioned to Syracuse a couple of weeks later. About three weeks ago, Espinosa was dealing with a thumb injury, according to Boras.

The Nationals will decide to bring up either Espinosa or Zach Walters. Whomever comes up, the player will be a backup infielder. Espinosa could have the edge because he is an excellent defender and could play shortstop if Ian Desmond needs a break.

Walters is having a far better season offensively, hitting 29 home runs with 76 RBIs. But he is not in Espinosa's class defensively. Walters has made 34 errors this season, most of them coming at shortstop.

The Nationals will not make a decision on Espinosa and Walters until the middle of the week, according to manager Davey Johnson.

Detwiler not close to throwing off mound

WASHINGTON -- Nationals manager Davey Johnson doubts that left-hander Ross Detwiler will pitch during the month of September.

Detwiler hasn't pitched since July 3 because of a disk problem in his back. There is no timetable on when he will get on the mound. According to Johnson, he has played catch, but nothing else.

"Nobody has talked about him, so I would imagine the next day or so I'll know more if he has accelerated the program or held back," Johnson said.

Worth noting

• Outfielder Bryce Harper had an X-ray on his left foot, which came back negative. Harper fouled a ball off his foot in the sixth inning of Sunday's 6-4 loss. He had a tough time getting off the ground, but he remained in the game and hit a game-tying home run an inning later.

Tyler Clippard has been the best reliever for the Nationals this season, going 6-2 with a 2.01 ERA, and Johnson said he has not ruled out Clippard closing games during the rest of the season.

Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.