John Isner pounded his way to a 6-4 first set win with six aces and seven forehand winners in Sunday’s Citi Open men’s singles final, using his arms to pump the crowd up after earning the match’s first break in the set’s final game.

Kei Nishikori opted for fewer theatrics when he came back to win the second set, 6-4, taking 100 percent of his first-service points in the set by moving Isner around the court.

If you paid attention, though, you could see a couple small shakes of Nishikori’s fist at the end of the third set’s third game. Down 15-40, Isner fired a 138-mph serve just wide. Nishikori managed to get part of his racket on a second serve sent toward his body, floating the ball up and across the net. Isner put the ball into the net three shots later in that rally to give Nishikori an edge in the match.

And when the match was over, the 25-year-old Nishikori sent both of his arms into the air and tilted his head back to look up before blasting the ball he was holding into the upper decks, celebrating a 4-6, 6-4, 6-4 win that will send him into fourth place in the world rankings.

Isner, meanwhile, will leave Washington with a third runner-up trophy after losing in the 2007 and 2013 final, although this year’s run to the final vaults him from world No. 18 to No. 12.

In their only previous matchup, Isner beat Nishikori, 6-4, 6-3, in the Miami Open in April.

“I think I returned really well today,” Nishikori said. “In Miami’s match, I was just playing the ball and waiting for his mistakes, but today I was a little different.”

On Sunday more than 80 percent of Isner’s first serves went in during the first set, and when Nishikori earned a break point, Isner took his blasts to another level. He hit an ace 132 mph down the T after Nishikori earned an advantage on Isner’s serve in the set’s fifth game. He followed that up with another big serve a point later to win the game.

But in the second set, Isner’s first-serve percentage dropped to 73 percent and Nishikori took advantage of Isner’s second serve, winning 72 percent of those points. Nishikori lost his first break-point opportunity when Isner served up a 135-mph ace in the set’s first game to earn a deuce, but Nishikori won that game two points later.

After going up a break in the third, Nishikori served out the match, giving Isner zero break-point opportunities in either of the final two sets.

“I just didn’t make enough inroads on his first serves, which a lot of times I struggle with,” Isner said, “And from there, I feel like he’s basically the best in the world from the baseline. He’s a great player and a great champion.”

Nishikori showed his versatility in the tournament’s final game, winning points with an overhead putaway, a backhand winner and consistent play from the baseline. He won championship point by sending Isner into the corner with a loud forehand and then putting away Isner’s return with a backhand volley.

Nishikori is 81-21 in deciding sets.

Bryan brothers triumphant

Bob and Mike Bryan needed less than an hour to capture the Citi Open men’s doubles championship with a 6-4, 6-2 victory over Ivan Dodig and Marcelo Melo, who beat the Bryans in the French Open final earlier this year.

The Bryans lost just five points on their first serve in Sunday’s match, surrendering zero break point opportunities while converting three of the five chances they had to break their opponents.

“I thought we were just guessing right and serving our spots really well,” Mike Bryan said. “It’s quite an accomplishment not to be facing break points against two of the best returners in the doubles game.”

Mike Bryan said the team’s coach watched the French Open final Saturday night and they talked about that loss before Sunday’s match. They changed some tactics as a result, including opting for an I-formation look more often than normal.

“Historically we are not an I-formation team . . . today we did,” Bob Bryan said. “Maybe they weren’t ready for it. They’ll be ready next time, so we’ll have to find something different.”