Andy Murray to face mother's boy Denis Istomin in US Open pre-quarters

Defending champion Andy Murray on Sunday set-up a US Open last-16 showdown with Uzbekistan's Denis Istomin, the world number 65 who is coached by his mother.

The third-seeded Briton, who ended his country's 76-year wait for a Grand Slam men's champion when he won his maiden major title in New York last year, eased past Germany's world number 49 Florian Mayer, 7-6 (7/2), 6-2, 6-2 to reach the fourth round.

It was a win built on an impressive 42 winners and seven aces.

Next up is 26-year-old Istomin, who has made the fourth round in New York for the first time and is almost unique on the tour in that he has been coached by his mother, Klaudiya, since his junior days.

"There's not loads of people that get coached by their parents. A lot of them do from a young age, but not so much when they're on the tour," said Murray.

"Obviously it works for him. Technically he's very sound. He's a good player. He hits the ball very flat and has had some good wins this week."

Murray admitted that he could even go down that road later in his career.

His mother Judy, who is Great Britain's Fed Cup captain, has regularly coached youngsters down the years.

"I wouldn't rule it out. She's a good scout and knows tactics. She hasn't played as a professional but having seen your son play in a Grand Slam final she understands the nerves and pressure," said the world number three.

"It depends I guess on how much one cares about that side. She enjoys all the statistics and technically she's taught kids from a young age."

Klaudiya Istomin played a crucial role in her son's development after a 2001 car crash hospitalized him for three months and kept him off the court for two years.

The accident happened at a third-tier event in Tashkent which left Istomin with a leg injury that needed 80 stitches.

"I need to thank my mother -- she believed I could play tennis again and that's why I came back," said Istomin in a recent interview.

Murray defeated Istomin -- who made the last 16 by beating Italian 20th seed Andreas Seppi 6-3, 6-4, 2-6, 3-6, 6-1 -- in their only other match, in the quarter-finals at Brisbane in January this year.

Despite winning in straight sets on Sunday, the 26-year-old Murray admitted he had struggled with the crushing humidity on Arthur Ashe Stadium.

"I was struggling breathing for most of the match. I just went to the toilet after the first set. It was quite a long set. When it's that humid, you tend to try and take on as much fluid as you can," said the Olympic and Wimbledon champion.