Miami Open: Andy Murray and Heather Watson progress in challenging conditions

The British hopefuls acclimitised to the gruelling conditions which have challenged other players

Andy Murray celebrates winning a match against Denis Istomin (Getty Images)

The heat and humidity of Florida is very different to the weather they grew up with in Dunblane and Guernsey respectively, but Andy Murray and Heather Watson both feel at home in Miami. While other players struggled to cope with the gruelling conditions, the two Britons both made good progress at the Miami Open.

Murray, who has a second home in Miami, put behind him the disappointment of his early exit at the hands of Federico Delbonis in Indian Wells to beat Uzbekistan’s Denis Istomin 6-3, 7-5 in his opening match. He will next face Grigor Dimitrov.

Watson, who is based at the Florida academy Nick Bollettieri founded in Bradenton, overcame stiff resistance from Yanina Wickmayer to win 3-6, 7-5, 6-3. In the last 16 Watson will take on Simona Halep, the world No 5.

Even in their evening match, perspiration was pouring off both players as Murray eased to a comfortable victory over Istomin. Murray, who regularly practises at Crandon Park during his Miami training camps, broke Istomin at the start of the match, quickly emphasising his superiority.

The only time when Istomin created any sort of opening was when the world No 76 broke serve in the fifth game of the second set. Murray’s concentration appeared to be broken when he noticed, at break point down, that one of the balls they were playing with was one of those used by the women in Miami. Different balls are used in the men’s matches.

“That's unbelievable,” Murray complained to the umpire. “That's one of the women's balls. I could have just hit a shot with it.”

The ball was taken out, but a clearly distracted Murray lost the following point and the game. “It's not right,” Murray said, continuing with his complaint to the umpire. “Do you know how different the balls are?”

However, the umpire insisted that the point would stand. “It's the same for both [players],” he said.

Murray, nevertheless, quickly rediscovered his focus. He broke to love in the following game and closed out victory after an hour and 38 minutes with his fourth break of the match when Istomin served at 5-6. If the Scot’s 24 unforced errors were evidence that he was a little way below his best, he still had good reason to be satisfied with his performance.

“I was hitting the ball cleanly, it’s just the shot selection tonight could have been better,” Murray told the ATP’s official website afterwards. “When you're break points down and trying drop shots or going for big shots from the wrong position, it makes it tough.”

Twice a champion in Miami and runner-up on two other occasions, Murray next faces an opponent who has given him trouble in the past. Dimitrov, who advanced with a hard-fought 7-6, 4-6, 6-4 victory over Delbonis, beat Murray in the Wimbledon quarter-finals two years ago, having also got the better of him in the semi-finals in Acapulco earlier in the year. Murray has won their three subsequent meetings, but their two encounters last year were both tight affairs.

Dimitrov has fallen from a career-high position at No 8 in the world rankings to his present position at No 28, but Murray described him as “a top-quality player”.

The Scot added: “We played here once before. I managed to win that one. I played a bunch of tough matches against him. I think the last one was in Cincinnati, where he had a match point. He had a bunch of chances to win that one and I managed to turn it around. I know I'll need to play good tennis and be a little bit more disciplined than I was tonight.”

Several players struggled in the demanding conditions. Rafael Nadal, complaining of dizziness, retired mid-match for the first time in six years when trailing Damir Dzumhur 2-6, 6-4, 3-0. Sergiy Stakhovsky and Thomaz Bellucci also retired from their matches, against Jack Sock and Mikhail Kukushkin respectively.

Aljaz Bedene was another who threw in the towel, but the British No 2’s problem was a sore wrist. Bedene quit when trailing Spain’s Roberto Bautista Agut 7-5, 2-2.

Heather Watson shakes hands at the net after her three set victory (Getty Images)

Watson followed up her impressive victory over Sloane Stephens by beating Wickmayer in a battle that lasted more than two and a half hours. The Briton, who had lost all three of her previous encounters with the powerful Belgian, lost the first three games en route to dropping the first set, but recovered well to level the match after a lengthy second set. The deciding set was tight and was decided by a single break of serve in the eighth game.

The heat and humidity were such that both players left the court for a complete change of their sweat-drenched clothing before the final set. Watson, nevertheless, returned later in the day to play a doubles match. Watson and Monica Puig were beaten 6-1, 2-6, 10-5 by Margarita Gasparyan and Monica Niculescu.

Halep secured her place in the fourth round by beating Julia Goerges 6-4, 6-1. The Romanian won both her previous encounters with Watson, at the US Open three years ago and at the French Open two years ago.

Jamie Murray, who is on the brink of claiming the world No 1 position in doubles, suffered disappointment for the second tournament in a row, having fallen one victory short of securing top spot in Indian Wells. Murray and his partner, Bruno Soares, were beaten 3-6, 6-3, 10-7 by Rajeev Ram and Raven Klaasen.