Less than two weeks ago, the Phillies were in a very bad place. Bryce Harper knew what his team had to do, but actually doing it was going to be far more challenging than just saying it.

“We have to win,” Harper said after the Phillies’ fifth straight loss dropped them to 9-14. “We have to go on a streak and win nine out of 10. It needs to happen.”

Thursday, the Phillies won for the ninth time in 10 games, finishing off a four-game sweep of the defending-champion Nationals with a 6-5 win in 10 innings at Citizens Bank Park.

• Box score

“I heard someone say that Bryce is a prophet,” manager Joe Girardi said. “I'm going to go to him to see what we need to do next.”

If Harper has his way, another four-game sweep -- this time against the Mets at Citi Field -- is on tap.

“As a team, I think we've gone out there and played to the best of our ability -- and we can still get better,” Harper said. “That's the thing about this team that I love; we can go out there and play this game, win ballgames and win nine out of 10. We've got a four-game set against the Mets; they're a good team, but I think we can go in there and do the same thing.”

Alec Bohm’s bases-loaded sacrifice fly scored J.T. Realmuto in the 10th, lifting the Phillies to their fourth straight win and an 18-15 record.

Zach Eflin allowed four runs over six innings, giving back a pair of early two-run leads. Five Phillies relievers combined for four innings of one-run ball, the lone hiccup coming on Michael A. Taylor’s go-ahead homer off David Phelps in the seventh.

But the Phillies rallied to tie the game in the eighth as pinch-hitter Andrew McCutchen made it 5-5 with a bases-loaded fielder’s choice in the eighth.

Playing their third extra-inning game under the new automatic runner rule of 2020, the Phillies found themselves in a jam in the top of the 10th. A one-out intentional walk and a two-out unintentional free pass loaded the bases, but Blake Parker got Brock Holt to ground out, stranding all three runners.

The Phillies took a different approach, bunting automatic runner Realmuto to third base to open their half of the 10th. Two intentional walks loaded the bases, but unlike the Nats, the Phillies cashed in with Bohm’s game-winning sac fly.

“It's really important; we don't have a lot of home games left, and we need it to carry over to the road,” Girardi said. “Every win is important at this point. We control our own destiny in a sense, and we need to play well. We just need to continue to take series and continue to do the things that we're doing.”

• Long time coming: Phils retire Allen's No. 15

The win moved the Phillies 1 1/2 games ahead of the Marlins for second place in the National League East, meaning they’re in the No. 5 spot in the postseason picture. They’ll return home from New York for a Tuesday doubleheader against the Red Sox, then hit the road for seven games in Miami over five days.

“This is the kind of baseball that we knew we could play,” Eflin said. “That's going to be a challenge. I don't know what the exact number is in however many days, but we know we have a lot of doubleheaders coming up. Honestly, I really wouldn't want to go through this with any other group of guys than we have in the clubhouse right now. Everybody's optimistic, everybody is all-in for this year, which is huge.”