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WASHINGTON -- A mischievous grin stretched across Washington Nationals manager Davey Johnson's mug while discussing which pitcher might fill in a gap in the rotation after Tuesday night's scheduled game against the Los Angeles Dodgers was postponed by rain.

"I'm sure 'Stras' would volunteer," Johnson said, chuckling at his reference to the famously shut-down Stephen Strasburg. "He is right-handed. He has been chompin.'"

For the first time since baseball returned to Washington in 2005, September pitching choices made by the Nationals' skipper really do matter. Despite coming off a three-game sweep by the Atlanta Braves, the Nationals entered Tuesday with the best record in the majors at 89-57, with magic numbers of three to clinch at least a wild-card berth and 11 to seal an NL East title.

Indeed, the Nationals announced they will put tickets for potential postseason games on sale Friday. The team hasn't finished higher than third place since arriving from Montreal.

"We're close, but the thing is, we're going to do what we've been doing all year, and that's kind of keep our head down and worry about one game at a time. Especially late in the season like this, if you get ahead of yourself, you can get yourself in trouble," reliever Drew Storen said. "We've done a good job all year of not really getting caught up in all that stuff."

With Tuesday's rainout, the Dodgers -- who entered the day a game out of an NL wild-card spot -- and Nationals will play a single-admission doubleheader starting at 4 p.m. EDT on Wednesday. Johnson expected to use Tuesday's scheduled starter, right-hander Jordan Zimmermann, and left-hander John Lannan; Dodgers manager Don Mattingly said Aaron Harang and Josh Beckett will be his pitchers.

Looking further down the line, Johnson figures he'll need to plug someone into what would have been Zimmermann's next start, on Sunday at home against the Milwaukee Brewers. Johnson knows he'd prefer to use a right-hander against a Brewers lineup that features 2011 NL MVP Ryan Braun -- which is why the manager joked about Strasburg, the All-Star who was recently declared done for the season because of reconstructive elbow surgery in 2010.

Johnson mentioned righties Craig Stammen and Chien-Ming Wang as possible fill-in starters for Sunday.

"I just don't want any of my good, young pitchers to (come back) on short rest at this point. And I don't think `Zim' has done it, and he's had a little bit of that inflammation there," Johnson said. "I think he could do it, and have no problem, but it's not something I'd like to do to any of those in the rotation, at this point."

There was good news on a couple of injured Nationals players, second baseman Danny Espinosa and left fielder Michael Morse.

Espinosa thought he might have a torn labrum in his aching left shoulder, but instead found out that it's a bone bruise in the socket. He got a cortisone shot Monday to relieve the pain and hopes to be able to play as soon as Wednesday.

"This is the best news that we could have gotten," Espinosa said. "If this was a rotator cuff tear or a labrum tear, it would have lingered the rest of the season. I would have had to have surgery in the offseason."

Morse, meanwhile, was slated to start in the outfield and hit fifth if Tuesday's game had been played. He missed the past four games with a bothersome left wrist.

"It's another day to heal," Johnson said. "Mike was feeling pretty good. He was good to go. We were anxious to have him in the lineup."

Johnson said that Morse was getting treatment Tuesday when they chatted.

"He had some electrodes attached to him. I don't know what that does, but he was getting electrocuted today when I was talking to him," Johnson said. "I guess that's helping it. So we'll see tomorrow."

Game notes

Reigning NL Cy Young Award winner Clayton Kershaw was examined by a hip specialist who said the Los Angeles LHP can continue to pitch without risking damage to his sore right hip, but the Dodgers want to keep him sidelined if the pain persists. The team said Kershaw would re-start a throwing program. The Dodgers said Dr. Bryan Kelly, who saw Kershaw in New York, agreed with team physician Neal ElAttrache's opinion that Kershaw's joint is pinched during the hip's rotation in his pitching motion. ... Nationals 3B Ryan Zimmerman was picked as the team's nominee for the 2012 Roberto Clemente Award. ... Lannan, who spent most of the season at Triple-A Syracuse, is 3-0 in three starts in the majors this season. He replaced Strasburg in the rotation. ... Dodgers closer Kenley Jansen, who has 25 saves, has been cleared to pitch again after being held out because of an irregular heartbeat. He last appeared in a game on Aug. 27.