US Open 2013: Mother knows best for both Andy Murray and fourth-round rival Klaudiya Istomin

Judy Murray may be one of the most famous mothers in tennis, but Klaudiya Istomina can go one up even on a woman whose offspring are both Wimbledon champions. Klaudiya is not only one of the few women who coach at the highest level of the men’s game but also works with her son.

Denis Istomin, who faces Andy Murray here on Tuesday in the fourth round of the US Open, has been coached by his mother all his life. "She's known me since I was born," the 26-year-old from Uzbekistan said with a laugh. "We have a good relationship and we understand each other very well. She always tries to help me with everything, not just tennis, but in normal life as well. She gives me good words to improve my tennis, my life, everything. I'm happy to be coached by my mum."

Judy Murray coached both her sons when they were young boys before they went on to work with other coaches. Andy can see a time when she might coach him again. "I wouldn't rule it out," the world No 3 said. "Maybe when I start to come to the end of my career, it might be something that would be nice to do. I know that tactically she's very good. She scouts a lot of matches and likes to watch videos of other players."

Istomin, who is through to the last 16 after a marathon five-set victory over Andreas Seppi, is clearly comfortable with his arrangement and is happy with the fact that his mother is the boss. "She says: ‘Do it like this and you will be OK. Just listen to me.' She's normally right. I will try to fight, but in the end I give in. When I started playing, she started to teach me tennis. She was playing, in national tournaments, so she knows tennis better than me for sure.

"I don't think the other players think it's unusual, though it's tough for players to travel with female coaches. Even to go into the locker room before the match and talk – they cannot do it. I always go outside and start to talk  before the match with my mum. So it's also tough for me as well."

Jimmy Connors was coached by his mother, Gloria, who would urge him to "play like a crazed animal". Marat Safin worked with his mother, Rausa, early in his career, but the only other current top player coached by his mother is Donald Young, who works with both his parents, Donald senior and Illona.

Judy Murray travels to many major tournaments, including the Grand Slam events, in her role as Britain's Fed Cup captain. She has also been working here as a TV analyst. While she never did any hands-on coaching with her younger son after Leon Smith – who is now Britain's Davis Cup captain – took over as coach when he was 11, she has maintained a strong presence in his tennis life.

"She always took an interest in who I was working with and what I was working on because she understands tennis and she's a coach herself," Murray said. "She was always in the background. She would always speak to my coaches and make sure I was doing the right things."

Murray can see what a good influence Istomin's mother has been on him. "Technically, he's very sound," Murray said. "He's a good player. He hits the ball very flat. I think he served extremely well today in his match. I saw some of the stats at the end. He's played well. He had a very good match with Novak [Djokovic] in Montreal. He's had some good wins this week  as well."

Istomin, who reached a career-high No 33 in the world rankings last year, had made the fourth round only once in his previous 21 appearances at Grand Slam events. He lost to Mikhail Youzhny in the last 16 at Wimbledon last year.

The world No 65 beat Nicolas Almagro, the No 15 seed, in the opening round and enjoyed revenge with his victory over Seppi. The Italian had beaten him in five sets in two other Grand Slam events this year, at the Australian Open and at Wimbledon.

Istomin is looking forward to the challenge of facing Murray. "I've just played him once, this year in Brisbane," he said. "I lost in two sets, but it was a close match. I will try to play the same tactics as I did there and we will see what happens.

"He's a great returner. He returns  almost everything. The key is my serve. I will try to serve better than usual. He is moving incredibly well on the court but I will try to move him more and try to beat him."

Istomin and Murray share a passion for football. Istomin is a Real Madrid fan, while Murray, given that he rarely has the chance to follow his first love of Hibernian, has adopted Arsenal as his second team. "I like the way Arsenal play," Murray said. "I like the way they run the club. I always enjoy watching them."

Before going out to play Florian Mayer on Sunday Murray watched Arsenal's victory in the north London derby with his press officer, who is a Tottenham fan.

"I actually went along to watch an Arsenal-Spurs game with him two years ago," Murray recalled. "We turned up 10 minutes late for the match. Arsène Wenger was suspended from being in the dugout and we had to get him to stand up to get through to our seats. I was so embarrassed to do that. He wasn't happy."