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7/19/2013 11:40 P.M. ET

LaRoche out with flu; Harper bats cleanup

WASHINGTON -- Just when it seemed like the Nationals finally had returned to full health, one of their marquee players was left out of the lineup in Friday night's 3-2 loss to the Dodgers.

Adam LaRoche missed the team's first game after the All-Star break with flu-like symptoms. Manager Davey Johnson hopes that LaRoche can return Saturday.

"He was coughing and whatever; I think he's just got a bad case of the flu," Johnson said before Friday's game. "He came in just to see the doctor, and he's going to stay in the back room and see if they can't get him well."

Johnson tinkered with the Nationals' lineup before the break, moving All-Star Bryce Harper to the top of the order, Anthony Rendon to the No. 2 spot and dropping Denard Span to seventh. Span was back in his usual leadoff role on Friday, with Rendon still second and Harper hitting cleanup.

But after another tough offensive performance, Johnson said that Harper would return to the leadoff spot if LaRoche is available on Saturday. The Nationals' skipper said that he likes his 20-year-old at the top of the order because it frees him up. Harper, however, doesn't have a preference one way or the other.

"Whatever he wants to do. It's up to him. He makes the lineup," Harper said. "I'll just try to have good ABs, and we've got [Zack] Greinke tomorrow, so we've got a lot of work ahead of us, and hopefully we can get things going and try to get some runs."

Davey says Detwiler unlikely for next start

WASHINGTON -- When asked if Ross Detwiler will be able to come off the 15-day disabled list and make his scheduled start on Tuesday, Nationals manager Davey Johnson sighed.

"I'm not hopeful at this point," Johnson said.

Detwiler has been on the disabled list since July 4 with a back strain. He played catch on flat ground on Thursday, but continues to have soreness in the back the day after throwing.

Johnson doesn't expect the left-hander to make his next start, or the one after that against the Mets next weekend. Rookie Taylor Jordan will continue to fill in for Detwiler in the Nationals' rotation.

"For me, [Detwiler] would have to throw today or tomorrow, and do a side [session] and then get out and pitch in a game. And I don't think we're going to do it by [next weekend]," Johnson said. "But I'm going to put that question to our great medical staff, see if they can't get him ready to go."

If Detwiler is unable to start in the Nationals' doubleheader against the Mets, Johnson said that he would probably start Jordan and Ross Ohlendorf rather than dip into the Minor Leagues for an additional starter.

After tough outing, Soriano tips cap to Dodgers

WASHINGTON -- The Nationals signed Rafael Soriano to a two-year, $22 million contract in the offseason because they wanted a shutdown closer. And for much of this season, he has lived up to that billing.

But less than a week after blowing his fourth save in a 2-1 loss to the Marlins, Soriano couldn't keep the score tied on Friday night. He gave up a solo home run to Andre Ethier in the ninth inning that proved to be the deciding run in a 3-2 Nationals loss.

"I don't know how he hit the ball," Soriano said.

Soriano entered Friday night ranked fourth in the National League with 25 saves. He threw four straight fastballs down and away to Ethier before throwing a slider on the inside part of the plate, a pitch that Soriano thought was well located. Ethier crushed it over the right-field fence.

"When I make mistakes, it's not easy for me," Soriano said. "But when I make the pitch, and they hit the ball good like tonight, there's nothing I can do."

Worth noting

• After sitting out the All-Star Game with lingering stiffness in his neck, Jordan Zimmermann threw a bullpen session on Friday and said that he expects to make his scheduled start against the Dodgers on Sunday.

• Right-hander Ryan Mattheus joined Double-A Harrisburg on Tuesday and continues to make progress in his Minor League rehab assignment, but Johnson thinks that he needs four more outings before returning to the Nationals.

Johnson specifically mentioned that he would like to see Mattheus pitch multiple innings in one outing.

"That's where he gets stretched out and where he needs to be," Johnson said.

• Entering Friday night's game, the Nationals were one of two teams in the Major Leagues with a winning record (48-47) and negative run differential (-14), joining the Yankees (51-44, -2).

Tom Schad is an associate reporter for MLB.com. Follow him on Twitter @Tom_Schad. This story was not subject to the approval of Major League Baseball or its clubs.