Fish makes waves now he's happy on the scales

Chips, cheeseburgers and pizza are kicked into touch as American transforms his career to become a genuine US Open contender

Mardy Fish needs to choose his hotel rooms more carefully. At his latest tournament, the Cincinnati Masters, his window overlooked a fast-food restaurant, which he would find himself staring at through wistful eyes. "I love pizza, French fries and cheeseburgers," Fish said. "And I haven't had any since that day on 28 September."

The date has special meaning in the American's household. Two years ago, Fish and Stacey Gardner married on 28 September in Beverly Hills. Twelve months later he spent their anniversary undergoing knee surgery. The 28-year-old former schoolmate of Andy Roddick also embarked that day on a lifestyle change that has transformed his career.

Facing several weeks of enforced immobility, Fish decided he would never have a better opportunity to go on the diet he knew he needed to follow in order to realise his full potential on the court. Maintaining a strict regime ever since, his world ranking has risen as rapidly as his weight has dropped. Having lost more than two stone, Fish has climbed to No 21 – he was No 108 in March – after a series of outstanding performances.

In the last three months he has won the fourth and fifth titles of his career, at Newport and Atlanta, and played in finals at Queen's Club and Cincinnati, where his run of five consecutive victories over top-10 players was finally ended by Roger Federer. With only Federer and Andy Murray enjoying better summers on the North American hard-court circuit, Fish is being talked about as a realistic contender to win the US Open, which begins in New York tomorrow.

Already one of the best servers in the game (when his first serve goes in he wins 80 per cent of the points, more than any other player), Fish has added speed and athleticism to his attributes, which has been evident in the way he has been chasing down drop shots in recent weeks.

He also feels stronger. "I've been able to train harder and longer," he said. "I've always worked hard, but I would work until I got tired and stop. Weighing 30lb less than I did before, I don't get tired as much, so I'm able to do a lot more. So as far as affecting my mobility, it's been everything. It's night and day. I feel extremely good on and off the court. I feel like a completely different player."

The turning point on the court was at the Miami Masters in March, when he beat Murray, the defending champion (who has also lost their two subsequent meetings). "He hadn't lost his first match in a tournament in 12 months," Fish said. "He's one of the best hard-court players in the world. That gave me the confidence, knowing that I was back. My knee felt good and physically I felt great."

Fish took his diet so seriously that he hired a nutritionist to cook and weigh everything he ate. His wife and physical trainer provided moral support by following the same regime, though he knew that Stacey was "definitely sneaking some ice cream or some yoghurt after dinner".

Alcohol, sweet fizzy drinks, cheese, pizza and hamburgers have been replaced by water, fish, chicken and vegetables. Vitamin pills are preferred to glasses of orange juice. He has a large breakfast followed by a smaller lunch and an even smaller dinner. For the first six weeks he avoided all carbohydrates and he tries to avoid eating anything after 6.30pm.

"It was a complete lifestyle change," Fish said. "I changed when I ate, what I ate and what I drank, as far as sodas and alcohol and things like that are concerned. I don't drink any sodas any more. The worst thing probably is some lemonade or iced tea or coffee in the morning. I've changed pretty much everything."

The reward has been a rapid improvement in what Fish describes as his third career. Having first broken into the world's top 100 eight years ago, he reached a career-high No 17 in the world rankings two years later, when he won a silver medal at the Athens Olympics. A successful return from wrist surgery in 2006 resulted in an award as the ATP's "comeback player of the year", while stage three of his career could be the most productive yet.

"I have done some things this summer that I have never done before," Fish added. "I have won more matches this year up to this point than I ever have. I also have a great opportunity to improve my ranking to where I've never been before.

"I knew that I had really put in a ton of work since September last year. I knew that I could look in the mirror and say that I have done all I can to put myself in this position and to be healthy and fit off the court and on the court. That in itself gives you a lot of confidence."