Rafael Nadal extended his sizzling summer with a first-time title. One set away from her own breakthrough, No. 1 Serena Williams wilted.

Nadal took advantage of the few openings he got against John Isner on Sunday, grinding out a 7-6 (8), 7-6 (3) win at the Western & Southern Open that added yet another title to his sensational summer.

The 27-year-old Spaniard won the championship in Montreal a week ago and has back-to-back hard-court championships for the first time in his illustrious career. He'd never even reached the finals in Cincinnati.

When his backhand down the line finished it off, Nadal flopped on his back and screamed.

"It means a lot winning two straight titles on hard [courts]," Nadal said. "It's just amazing for me. I never did something like this in my career.

"So it was an emotional moment."

Williams had never won a Cincinnati title, either. Like Nadal, she was trying for her second championship in two weeks, fresh off her championship in Toronto.

She dominated the first set, then fell apart, giving No. 2 Victoria Azarenka a chance to rally for a 2-6, 6-2, 7-6 (6) win that ended Williams' 14-match winning streak. Williams committed 58 unforced errors that turned the momentum.

"I just felt really off this whole week, but I was surprised to be in the final and surprised to be doing well," Williams said. "So I don't know, there's a few factors. I think what matters most was just fighting the whole time and survived to the end."

The week in Cincinnati provided a preview for the U.S. Open, with the men's bracket more jumbled at the top.

"I would say Rafa is the favourite going to the U.S.," Isner said. "Clear-cut? I wouldn't say that. I think he'd probably say the same.

"If you compare maybe him and Serena, I think Serena is probably a more clear-cut favourite on the women's side than Rafa is on the men's side, but he certainly is going to be super tough to beat considering he just won back-to-back Masters events on hard courts."

At the moment, nobody's got more going for him.

New career benchmark

Nadal's five Masters titles this season are a career best. He's tied with Novak Djokovic for most Masters titles in a season since 1990. He's won seven of the nine Masters events during his career.

Nadal has dominated the tour after overcoming a knee injury that sidelined him for the last part of 2012. The win on Sunday gave him a career-best mark of 53-3 this season. He's reached the finals in 11 of his last 12 tournaments, underscoring his consistent excellence.

He had one of his biggest challenges Sunday — the 6-foot-10 Isner, who had the tournament's nastiest serve and the crowd at centre court behind him.

Nadal survived a pair of set points in the opener, sending it to a tiebreaker. The crowd chanted "Let's go Isner!" during a changeover during the tiebreaker, which ended with Isner dumping a service return into the net and Nadal pumping his fist.

Isner didn't waver, keeping up with a serve that topped out at 141 mph. Nadal survived the only break point of the second set, taking it to another tiebreaker. The crowd chanted Isner's name again, but it didn't help. He hit a backhand and a forehand into the net, allowing Nadal to go up 5-1 in the tiebreaker.

Nadal finished it with a backhand passing shot from the baseline, then plopped on his back. He never got to a break point during the match, but won it by playing so well in the tiebreakers.

"I have to be patient and wait for my opportunities," Nadal said. "And I waited."

Effort to be proud of

Even with the loss, it was quite a week for Isner.

While Nadal spent last week winning the Rogers Cup, Isner was knocked out in the first round and fell to No. 22, the first time in the 40 years of ATP rankings that no American man was in the top 20. He'll move up to No. 14 next week after reaching the finals in Cincinnati on the strength of his serve.

The 28-year-old American upset No. 1 Djokovic in the quarterfinals at Cincinnati, one of the best moments of his career. Since July, Isner has won 16 of his 20 matches, making him into a dangerous player heading into the U.S. Open.

"So I played a lot, and I've won a bunch of them," he said. "And a lot of very, very encouraging results."

On the women's side, Williams has dominated, going 60-4 this season. She has never done well in Cincinnati, and was eager to win on Sunday for a career-best ninth title of the season. All the statistics were in her favour — a 12-2 career record against Azarenka, including a three-set win for the U.S. Open title last year.

She won the first set in 26 minutes, dropping only 11 points. Then, she got sloppy in a second set that bogged down. The sixth game went to deuce 12 times before Williams held serve on the 30th point. Williams appeared to wear down and lost the set 6-2.

It was reminiscent of their finals match at the U.S. Open last year, when Williams took the last four games to win 6-2, 2-6, 7-5. This time, Azarenka held on, winning a couple decisive points off Williams' serve in the tiebreaker.

Tournament officials handed her an oversized bottle of champagne when she finished off the 2-hour, 29-minute match. Azarenka was hesitant to pop the cork, until Williams encouraged her. She sprayed the court and took a sip.

"I need to get more practice because I felt like I'm not directing it too well," she said.