Ivan Lendl returns to tennis to coach Andy Murray.
Credit: AP

"Come on, bury him," Ivan Lendl says to Andy Murray. "He's talking shit about how slow you are." It's Murray's first practice since he won the Sony Open in Miami in March. Lendl – once the best tennis player in the world, with eight Grand Slam wins – is now his coach, and wants to see a fight. It doesn't matter that Murray and his hitting partner, Daniel Vallverdu, are only playing mini tennis – a game of dinks, slices, and angles that uses a tiny part of the court. In all its forms, for Lendl, tennis equals confrontation, and the goal is always the same: dominance. "Make him suffer," he says to Murray.

In the 1980s, as John McEnroe and Jimmy Connors belted flashy winners and berated umpires, Lendl coolly battered his opponents with machinelike forehand flurries. "There was no act," says Brad Gilbert, who lost to Lendl all 16 times they played. "The guy was rough. He gave you nothing."

Nineteen years after he retired with a bad back, Lendl, 53, is trying to bring out that same merciless attitude in Murray. Last year, in their first season together – and Lendl's first ever as a coach – Murray reached his first Wimbledon final, beat Roger Federer for the gold medal at the London Olympics, and outlasted Novak Djokovic at the U.S. Open to win his first Grand Slam title. "Andy was already a great player," says Darren Cahill, who coached Andre Agassi and put Murray and Lendl in touch. "But he needed that extra bit of belief when you step on the court against guys like Federer, Nadal, and Djokovic."

Lendl was dubious about coaching. He didn't pick up a racquet for 14 years after he retired. He despises life on the circuit – he'd rather sit at home watching hockey with his German shepherds, Gunner and Chip, or play golf with his daughters (three of his five girls are exceptional players, and one hopes to turn pro after college). But Lendl knew what Murray was up against: Before Lendl was dominant, he lost his first four Grand Slam finals. So when Cahill called in 2011, Lendl asked him, Murray, and Vallverdu to meet for lunch at a Florida strip mall. "It was at some Italian place next to a hairdresser's – it wasn't some flash meeting," Murray says, looking aghast when asked about the food. "It says a lot about him."

Murray liked that Lendl wasn't a career coach who would kiss ass for a paycheck. "I don't think every coach is great at being completely honest and open," says Murray. "Sometimes guys want to protect their job."

"I don't give a flip," Lendl says between practice sessions. "I told him, the moment you're tired of me, tell me. I'll go back to playing golf." Lendl takes little credit for Murray's success. "You can't measure that," he says. "It's about Andy, not me."

Today, Lendl has driven two hours to Boca Raton from his home in Vero Beach to meet Murray, who lives in Miami, 50 miles away. They are training for the clay-court season at the Boca Grove country club. Murray arrives with Vallverdu; his trainer, Jez Green; and physiotherapist Andy Ireland.

Green, a high-tech trainer who likes to say he conditions players' movements, not their muscles, has known Murray since he was a teenager. Ireland, an acupuncturist, keeps meticulous notes on Murray's workouts. Lendl gives Green and Ireland final say on Murray's nutrition and workload. "After a few little battles about my philosophy and his philosophy, I found he listens," Green says.

On the practice court, Lendl urges Murray to watch for the slightest sign of weakness across the net. "Take more swinging volleys," Lendl says after Murray waits one beat too many to unload on a weak shot. "You let them bounce in Miami."

What intrigued Lendl was that for all Murray's hard work and success, he'd still hang his head against the likes of Federer and Djokovic, as if he didn't belong in their company. Lendl, the man everyone mistook for a tennis robot, could see that Murray needed to loosen up. "You have to have fun," Lendl says. "Once you work hard and do everything you can, the result is irrelevant. The key is to have conviction that what you are doing is the right thing."

At last year's Wimbledon, Murray lost to Federer in the final, but he has no regrets. "It was the first time I responded well to losing in the final of a Slam," Murray says. At the Olympics, he pummeled Djokovic and Federer in back-to-back matches. When he blew a two-set lead against Djokovic in the U.S. Open final, Lendl wasn't worried. "I could see Novak was tired," he says. "Andy worked him so hard." In the fifth set, Murray pulled away.

"Andy used to get to those matches, and he wasn't sure what style of tennis he needed to play," Cahill says. "I think the best is yet to come for them."