WASHINGTON -- It's been expected that Edwin Jackson and Ross Detwiler, the Nationals' fourth and fifth starters this season before Stephen Strasburg was shut down, would fill the No. 3 and No. 4 spots in Washington's postseason rotation. But manager Davey Johnson said Wednesday that John Lannan, who has occasionally filled in this season and took Strasburg's spot for the stretch run, remains a candidate.

When the Nationals were National League East bottom-feeders, Lannan was at the top of the rotation and made 122 starts from 2008-11. But he was the odd man out this spring, and has gone 4-1 with a 4.13 ERA in six spot-starts.

Lannan has pitched well when called upon -- particularly against the Braves -- which is why Johnson is leaving the door open in case the Nats open the Division Series with Atlanta.

"We don't even know who we're playing," Johnson cautioned Wednesday. "And it could be two series later. I'll address it when it's time to address it."

Lannan's first big league start of the year came against Atlanta in the second game of a July 21 doubleheader. Atlanta had won the first game and was closing in on the Nats in the standings before Lannan scattered two runs on five hits over seven innings.

Jackson, who started the season finale on Wednesday in Washington, came in 1-2 with a 7.92 ERA since the beginning of September. Detwiler is 2-2 with a 3.73 ERA in that span but has given up eight runs in his last two starts (both losses), spanning 7 1/3 innings.

Robinson's first pitch to be prior to NLDS Game 3

WASHINGTON -- Baseball Hall of Famer Frank Robinson will throw out the first pitch before Game 3 of the National League Division Series at Nationals Park, according to a baseball source. The Nationals have yet to formally make an announcement.

Robinson was the Nationals' first manager, guiding them to a combined 152-172 record in 2005 and '06. Their best season was in '05, when they went 81-81 and were in the pennant race until the middle of September. Robinson also managed the Expos from '02-04. Montreal had a record above .500 in two of those three years.

"It's an honor for me. I appreciate them reaching out to me and asking me to do that. ... I feel very honored and gracious," Robinson said on Monday when the invitation was first extended to him.

Shortstop Ian Desmond was happy to learn that Robinson will throw out the first pitch. It was Robinson who gave Desmond his first chance to prove himself in Spring Training in 2005.

"Frank is a role model of mine. He was not only great on the baseball field, but he is a good man, a good manager," Desmond said. "He played a big [part in my career]."

Johnson says Nats have all the experience they need

WASHINGTON -- Even with the Nationals' youth being one of their most prominent season-long storylines, Davey Johnson has no concerns about his team's perceived lack of postseason experience.

Six players on the Nats' active roster have seen playoff action, though only two -- Adam LaRoche and Jayson Werth -- are everyday players. Werth leads all Nationals with 44 playoff games played, while Mark DeRosa is second with 22. But DeRosa figures to see few postseason at-bats off the bench when Washington opens its National League Division Series this weekend, and LaRoche has played in just eight playoff games. Reliever Mike Gonzalez has also appeared in eight, and behind him, Edwin Jackson has played in seven and Chien-Ming Wang in four.

But the Nats' skipper, between 13 years as a player and 16 as a manager, believes he has all the postseason experience the Nationals will need in their first playoff series since returning to Washington.

"The beauty of it is you've played alongside each other all year long and you know what everybody's capable of doing," Johnson said. "You feed on the energy of knowing that the guy behind you's pretty good. So you don't need to have a whole lot of guys with postseason experience.

"And I've got a ton of it. It's always been the same way, whether I've had a young club or a veteran club or whatever."

"I just think that [Johnson] being himself and letting us do our thing, he has a lot of trust in his players," said Werth. "He believes in us, and if you look around the room, we all feel that. That helps guys play, that helps guys relax and be themselves. Just him being our skipper is good."

With young players like Bryce Harper at the forefront of the team, the Nationals have faced the issue of their age all season long. Indeed, Washington is the seventh-youngest team in baseball, with an average age of 27.8 years old.

But the club's six players with postseason experience have a combined 93 playoff games played, including four starts apiece between Jackson and Wang. Werth reached the World Series twice with the Phillies, and hit seven home runs in the 2009 playoffs, while Jackson also has pitched in two World Series games.

"You gain your experience by playing 162 games and winning those games, winning those series. That's how you gain your experience," Johnson said. "We treat every game as a big game, so now we have some more games, you don't prepare any different than you prepare for any of the other ones [since] April 3."

Worth noting

• Johnson said that some players who do not make the postseason roster will remain with the club and others will go down to Florida to continue to work out.

"Some we'll keep here, some we'll send there," he said. "The guys that we'll probably keep here will be pitchers. [Stephen Strasburg] ... and company. Probably three other guys."

Johnson still isn't showing his cards about who will make the roster, but he said Wednesday he's been impressed with the recent performances of relievers Zach Duke and Christian Garcia.

• Johnson said the Nationals will travel Friday, regardless of who they play in the first round. If they play Saturday in San Francisco, they'll fly early Friday morning. If the Nats have to wait to learn the winner of the Wild Card game in advance for Sunday's game, they'd likely have to wait till later Friday night.

The team will have Thursday off, but Gio Gonzalez and Jordan Zimmermann -- the Nationals' Game 1 and Game 2 starters, respectively -- will likely come to the park and throw.

• Johnson had this to say about Bryce Harper's chances for the NL Rookie of the Year Award as he goes up against Cincinnati's Todd Frazier and Arizona's Wade Miley: "He'd get my vote. I wouldn't trade him for any of the other two. The year he's had, I think he's been energy, scored a lot of runs for us, got on base a lot, played great defense. He's been great. I guess [Frazier is high on the list, too], because we both have similar records, but different opponents. But [Harper] gets my vote."