Alexander Zverev returns against Andrey Rublev on Sunday in Mason, Ohio. Photo: VCG

Alexander Zverev backed up his Olympic triumph with a fifth ATP Masters 1000 title as he crushed Andrey Rublev 6-2, 6-3 in Cincinnati on Sunday.

The German needed less than an hour against his longtime childhood friend and rival to lift the trophy and put himself into a solid position with the US Open starting a week from Monday.

"The US Open starts in a week's time, so obviously I want to keep it up and I want to maybe play even better there," Zverev said.

Zverev showed no effects from the stomach discomfort which forced him to take a medical timeout during his draining semifinal victory over Stefanos Tsitsipas on Saturday.

Zverev won his 11th match in a row and his fifth against Rublev, a player he's been playing since their junior days.

The German came into the week with six defeats in prior Cincinnati appearances, but turned that negative on its head.

"My first win here was on Wednesday and now I'm holding the title four days ­later," he said. 

Zverev kept his unforced error count to just six, though he was out-aced by Rublev 11 to six.

The third seed produced 16 winners and broke Rublev five times.

Zverev's only minor hiccup came as he was broken while serving for victory leading 5-2 in the second set.

But he closed out the convincing win a game later with a timely break back as Rublev found the net with a return.

"Until the end I was playing ­pretty good tennis," Zverev said. 

"I didn't do a big celebration at the net since Andrey and I have been best friends since we were 11 or 12.

"With my Olympic gold and this fifth Masters I'm really looking forward to New York."

Women's world No.1 ­Ashleigh Barty was similarly impressive in winning her fifth title of the season at the combined ATP and WTA event, cruising past Swiss wild card Jil Teichmann 6-3, 6-1.

The Australian, who will keep a firm grip on the No.1 ranking as the final Grand Slam of the year approaches, took control midway through the opening set and was never truly threatened.

"It's been an awesome week, with each match it was getting progressively better," Barty said.

"Today I was able to trust myself and play with confidence, which was important in a big final.

"I'm excited to get ­matches in tough conditions here in Cincy going into New York."

The double Grand Slam champion will on Monday start her 83rd consecutive week in the No.1 spot.

The win in her 19th career singles final gave Barty a 13th trophy, including seven from her last eight ­finals appearances.