Germany's Alexander Zverev beat Australian teenager Alex de Minaur 6-2, 6-4 to retain his Citi Open title in Washington on Sunday.
Zverev's serve played a big role in the victory, his third of the year, as the World No 3 won all but two of his first-serve points in the final, which lasted 74 minutes.
"Happy with how I played today and happy how the whole tournament went from start to finish, from the first match to the last point I felt in control," Zverev told Tennis Channel.
"Every single match I thought I played well."
The German, now with nine career victories, became the tournament's first repeat champion since Argentine Juan Martin del Potro in 2008-09.
With the 21-year-old going up against fellow youngster Minaur, 19, Zverev told the crowd: "This final could be the final of the next 15 years, so I hope you guys all enjoyed it.
Asked how much better he is now, Zverev replied: "Definitely stronger physically. In general I’m a better tennis player."
De Minaur added: "He really deserved it and played too good today."
Obviously struggling from fatigue, the Australian dropped the opening four games of the first set but fought back in second.
De Minaur drew the crowd's applause when he hit a winner to hold for 3-4, after saving three break points to avoid a double-break deficit.
He saved two match points on his own serve at 3-5 but Zverev clinched the victory when de Minaur hit a backhand into the net in the next game.
Although beaten, de Minaur, once ranked 208 in the world, will soar into the top 50 for the first time when the new rankings are released on Monday, rising 27 spots to number 45.
Zverev will have little time to relax as he plays in next week's Rogers Cup in Toronto where he is the defending champion although he has a bye into the second round.
Kuznetsova survives four match points to win in Washington
Svetlana Kuznetsova fended off four match points en route to a 4-6, 7-6(7), 6-2 win over Czech Donna Vekic in the Citi Open final in Washington on Sunday.
It took a remarkable comeback by the 2014 champion to win an 11th consecutive match in the US capital and secure her 18th career title.
"There’s something going on in Washington," Kuznetsova said.
"I’ve been here two times and I’ve never lost."
Kuznetsova, the 2004 US Open and 2009 French Open champion, was once ranked as high as second in the world but has fallen to No. 128 after injuries and undergoing wrist surgery last November, making her the lowest-ranked player to win the tournament.
The Russian's previous WTA title came at the Kremlin Cup in 2016 and she looked set to miss out on adding another Washington crown to her resume when she miscued a backhand into the net to give Vekic a third match point at 6-5 in the second set.
Kuznetsova crushed a forehand return winner to level at 6-6 but a Vekic forehand set up a fourth match point at 7-6, only for the Croat to hit a makeable forehand wide on the next point.
That saw the tide turn, as Kuznetsova's defence brought out errors from seventh seed Vekic and the Russian took the next two points to win the tiebreak 9-7.
Kuznetsova then swept to a 5-0 lead in the deciding set with her eighth ace of the match, and she claimed victory when Vekic hit a forehand wide.
“Sorry I didn’t win today," the tearful Czech said.
"Tennis is not an easy game but I love this sport and hopefully I can be in a few more finals and win some more finals."
Buzarnescu dominates Sakkari to win first WTA title
Mihaela Buzarnescu cruised to her first WTA title by dominating first-time finalist Maria Sakkari 6-1 6-0 at the Silicon Valley Classic on Sunday.
The 30-year-old Romanian lost 19 points and needed just 73 minutes to wrap up the final.
“I was able to take all the emotions away and keep focused, and try to take it as a normal match, not as a final,” Buzarnescu told reporters.
“Even after the first set, I thought she could come back, so it was really not easy. After leading 3-0, I thought I could really win the match.”
Greek Sakkari, 23, had proven capable of dramatic comebacks after stunning Venus Williams and Danielle Collins en route to the final but there would be no magical turnaround on Sunday.
Buzarnescu won the first five games in less than 20 minutes before Sakkari got on the board. “It was not easy. I woke up and I was still tired from yesterday, but she was very good today,” said Sakkari, who incurred 34 unforced errors.
“I wasn't moving great, and it's one of my weapons, so it wasn't easy after two long matches and very intense days. I gained confidence and experience and it was a great week for me.” Buzarnescu, who just a year ago was No. 142 in the world, will rise to 20th when the updated rankings are released on Monday.
“Maybe people will look differently at me now, but I don't want to change anything - just think of the good moments, and play,” said Buzarnescu, who lost in two finals this year.