PHILADELPHIA -- Like the flowers that flourish so well in the spring and summer, the Washington Nationals, in full bloom now, must guard against wilting in September.

So often young teams that have never tasted the euphoria of a late-season pennant race have trouble handling down-to-the-wire pressure.

The Nationals, with the best record in the Major Leagues, have built their amazing summer around a core of young, energetic players and superb pitching, but most of these athletes have never played for a division leader poised for the postseason.

Will the Nationals choke on their unexpected success, or shrug off the ever-present distractions that come with being No. 1 for the first time?

Will 19-year-old Bryce Harper sometime in September pinch himself and utter, "Is this really happening to us?"

Davey Johnson, who's built his managerial reputation around an ability to coax every ounce of ability out of players, poo poos the thought. He's not about to let the this team collapse down the stretch.

"We're more prepared to do battle right now than at any point in the season," Johnson said Friday before the Nats played the Phillies. "We've gone through the tough times. For me to worry about the next 38 games doesn't make sense."

The Nationals entered the weekend series against their one-time nemesis, the Phillies, with a comfortable lead over Atlanta in the National League East. Their 16-6 August record is the best in the NL for the month and this team hasn't had a losing month. It is 28-13 since the All-Star break.

Watching the Nationals play the five-time division champion Phillies at Citizens Bank Park was in stark contrast to battles between these two teams as recently as a year ago, when Philadelphia was en route to 102 victories.

The Phillies are buried in third place now, out of the race, while the Nationals are on pace to win 101 games. The fortunes have changed as the Nationals are trying to prove how good they are and the Phillies are reduced to the role of spoiler -- a total reversal from years gone by. In fact, after Friday night the teams have eight remaining games with each other, including a season-ending series in Washington.

"If we take care of business, we have a chance to do something special," said All-Star third baseman Ryan Zimmerman, and referring to the large number of injuries the team has endured, added: "Half of us haven't even played three-quarters of a season."

That's exactly why Johnson believes the Nationals should be strong down the stretch.

"The first two months we were in a dogfight," he said. "Our offense was missing a lot of pieces, our bullpen was out of whack -- our setup guys were closing. We had a lot of role changes, so now that everything is settled down we've gone through the tough times.

Johnson talked about center fielder Jayson Werth going down on May 7 with a broken left wrist, Zimmerman with a shoulder problem, and injuries to catchers Wilson Ramos, Jesus Flores and Carlos Maldonado.

"The young guys have come in, expressed their talent and proved that they belong here," Davey said. "That's the biggest thing -- where you have patience and don't put pressure on them. Steve Lombardozzi, Tyler Moore, Danny Espinosa, Bryce Harper, Ian Desmond -- the coaches and myself have not let them get off on a tangent or get too discouraged."

Making Johnson's job easier is the fact these youngsters have matured quickly.

"Last August I said if we play up to our potential (in 2012), we can win the pennant," Davey recalled. "We've done that and more. Like when we lost our closer, Drew Storen, for half the season. All of this caused an adjustment in roles. The job [the youngsters] did in holding the team together was the tough part."

But the tempo picks up in September, especially for young teams that have never won a division title or been to the postseason.

"Every situation is different, but with Washington many of their young players like Gio Gonzalez have a lot of experience," said Phillies manager Charlie Manuel. "The kid playing in the outfield [Harper], the energy he brings, his passion, and the excitement of getting a chance to go to the postseason and the possibility of playing in the World Series really sends a big message."

Manuel adds, "The veterans have a strong influence and Davey Johnson has been around a long time -- knows a lot about the game. The coaching staff is really energetic and they work well together. They have a lot going for them and I can't see them letting it get away from them."

Werth put it this way: "We're still a young club, a little inexperienced still, but it's coming. You can see the difference as the season has gone on. We're still going to be young at the end of the season, we're still going to be young next year, and young for awhile."

Veterans such as Werth, who went to the postseason four years (2007-2010) with the Phillies and helped them win the 2008 World Series, can be an immense help to their young teammates as the pennant chase intensifies.

"We've had some conversations, but nothing too serious," Werth said. "I think the veteran guys are dealing more with the day-to-day stuff right now -- and keeping things headed in the right direction."

Reliever Storen said the other day there's a risk at this juncture looking at how great the season has been and what lies ahead.

"When we are done, we can look back," Storen said. "Once you step outside the box and start looking in, that's when the trouble starts."

NL East opponents may not like to hear this, but Johnson is convinced even better days are ahead.

"People like to say, 'Now it's crunch time, how do you motivate them?'" he said. "To me, they've gone through the hard test. So now that we've gotten a little bit healthy, we're much better prepared."