Milos Raonic didn’t lose a set throughout the Citi Open, beating Vasek Pospisil in an all-Canadian final on Sunday for the sixth title of his career. (Katherine Frey/The Washington Post)

When Milos Raonic hit his final shot past Vasek Pospisil, the world’s seventh-ranked player leaped, mouth open, and finally celebrated. Raonic had gone through the Citi Open field without dropping a set, stoic the entire way. But this tournament-winning point was reason enough to show some emotion.

In the first all-Canadian ATP Tour men’s final in the Open era, Raonic beat Pospisil in straight sets, 6-1, 6-4, at William H.G. FitzGerald Tennis Center in Rock Creek Park. All week, he was calm, reserved and calculated, but winning his first event of the summer hard-court swing earned him some happiness — for about an hour.

“I have a flight in a few hours,” Raonic said.

Raonic wasted little time in the 1-hour 7-minute match. With Pospisil serving first, Raonic got a break in the first game. Pospisil said Raonic has the best serve in tennis, and it showed when he touched 143 mph on a second serve.

“You can’t read his serve at all,” Pospisil said. “You have to play a guessing game because it’s so accurate and fast. You can’t just stand there and react. If you do, he’s just going to ace you, so you have to guess, and then you can get aced doing that.”

Pospisil played in the tournament’s last match Friday night, and it was postponed at the start of the third set because of rain. He had to finish that match Saturday morning, then play the semifinal later that night. He entered Sunday afternoon’s match fatigued. Raonic took advantage; he was 3 for 5 on break points in the first set, winning easily to give himself an edge entering the second, in which he served first.

Both players held serve in that set until Raonic gained a 5-4 advantage. Raonic had followed the same script in previous matches, flipping a switch as soon as he was within range of winning the set. Leading 40-30, Raonic launched a backhand passing shot winner past Pospisil, who was near the net. Raonic jumped and looked in the direction of his coach. He was broken just once in the tournament, by American Jack Sock in his first match.

Raonic entered the tournament as the seventh-ranked player in the world, and that will improve to No. 6 after winning his most significant tournament thus far. Pospisil’s ranking will go from No. 36 to No. 28.

“I think I’m playing at a high level,” Raonic said. “I think the number I have beside my name is not a coincidence. I don’t think it would be a coincidence for that to get smaller.”

Raonic and Pospisil accepted their trophies with four Canadian flags waving behind them, fans proudly lofting them throughout the match. Pospisil said it felt like he was playing before a Canadian crowd. Raonic turned to specifically address the fans with the flags during the trophy ceremony.

The crowd was divided on what player it preferred. Chants of “Let’s go Vasek” rang out before being combatted by shouts of “Milos.” One woman finally called out, “I love you both!”

“It’s Canada Day in Washington today,” Tennis Canada President and CEO Kelly Murumets joked.

Raonic tried not to think about the Canadian weight on his shoulders. He had visited the Canadian Embassy earlier in the week, and the Canadian ambassador gave him a private tour. But playing in the first all-Canadian men’s final made it feel as if he had more to lose.

Raonic, 23, and Pospisil, 24, last played in the semifinals in Montreal, with Raonic prevailing in three sets. Pospisil still remembers the first time the two played as teenagers about 10 years ago. Pospisil won, 7-6, 6-4, claiming his first national title. Raonic bloomed later.

“The first time we played, we were 14, and he wasn’t serving the way he is now,” Pospisil said. “He had a growth spurt, and when he was 15 or 16, he was serving incredibly well for such a young kid, so back then, it was pretty obvious that if he could get his ground stroke together, he could be a great player.”

The two are the faces of Canadian tennis, along with Wimbledon finalist Eugenie Bouchard. Their match was broadcast during qualifying at the Rogers Cup in Toronto, where fans gathered outside to watch. Murumets said the success of the Canadian players has contributed to more Canadians playing tennis.

The Rogers Cup means the most to Raonic outside of the four Grand Slams, so he won’t waste any time celebrating the Citi Open, not that it’s in his nature anyway.

“I should,” Raonic said. “But sometimes I can get caught up in what the next goal is.”