WASHINGTON -- Before the start of this series, a black T-shirt was draped along every chair in front of each player’s locker inside the Nationals’ clubhouse, with red lettering on the front that read “Stay in the Fight” with the phrase “162+” on the back. The shirts were the creation of manager Dave Martinez and director of mental conditioning Mark Campbell, and they served as a message before the start of the biggest week of the Nats' season to date.

The Nationals responded with their first three-game sweep of the year, completed by a 7-4 victory over the Phillies on Thursday night at Nationals Park, a statement that these Nats are not ready to give up on their postseason hopes just yet. Washington has spent the past few weeks slowly climbing back into contention, and has now won 17 of its past 24 games.

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In nearly every phase of the game, the Nationals are clicking. Their lineup is deep and dangerous, their starting rotation is serving as the steady foundation and their bullpen is suddenly competent after struggling for the first two months of the year.

“This is what we anticipated from the get-go,” manager Dave Martinez said. “They are playing really well.”

Even though starter Erick Fedde struggled with his command, the offense picked him up with a four-run sixth inning, powered by a solo home run from Anthony Rendon and a three-run dinger from Victor Robles. The Nationals have hit at least one homer in six straight games, the longest streak in team history (2005-present), and they have clubbed 15 homers during that span.

They are also playing some of their best defensive baseball of the year, highlighted by some strong defense Thursday from shortstop Trea Turner, whose diving stop in the second inning not only prevented a single from rolling into the outfield, but he then cut down Scott Kingery at the plate trying to score from second.

Then, the Nationals turned it over to the bullpen and their newfound trio of Tanner Rainey in the seventh, Wander Suero in the eighth and Sean Doolittle in the ninth. They closed it out to seal the Nats’ fourth win in a row, matching a season high.

“I think baseball's hard to explain sometimes, because we've won, I feel like, in many different ways lately,” Turner said. “That's what good teams do. You can win 1-0, you can win 10-9, blow somebody out or win a close game. I think we have a deep enough lineup and roster to do that. Some days the bullpen's going to pick us up, some days the starting pitching, some days top of the order, bottom of the order -- whatever it may be. Lately, we've been doing it all.”

At the start of the day Thursday, the Nationals had already overtaken the Mets for third place in the division for the first time since April 23. And as Washington has begun surging, Philadelphia has started to fade. The Nats sit just three games back of the Phils, who have lost five of their last six, for second place in the division. They are only 3 1/2 games back of the second NL Wild Card, though they have five teams in front of them.

Now comes an even stiffer test -- the first-place Braves, who begin a three-game set at Nationals Park on Friday night. The Nationals are undoubtedly playing some of their best baseball of the season, but they still trail Atlanta by 7 1/2 games in the division, making this weekend a golden opportunity to continue making up ground.

“We have a good team, and we’re playing pretty good,” Robles said through team interpreter Octavio Martinez. “And things have been going our way. We’ve been working hard for this, and now we’re back in the race. All we can do is go out and keep putting in the effort we’ve been putting in, and hopefully the results keep coming our way. But it definitely gives us a big boost in confidence.”