David Bailey believes that technique and power can only take a player so far in tennis. It's their feet that help a champion make great strides in the game.
The Australian has come up with his own coaching method based on the principles of footwork, which he taught to coaches during a workshop in Jakarta in January. Today's power game is driven by improved strings and rackets, which compensate for a mistimed shot or faulty technique. Still, Bailey says, knowing how to move right on the court can make a world of difference to a player's game.
"Having good footwork enables you to be more efficient in your movement so you don't get tired," he said. "In soccer, if you can hit off both feet then it's better, and it's the same for tennis. If you hit your backhand off one foot all the time, then you're more likely to get injured. I've seen players with a lot of talent but they get stress fractures in their backs because they were always hitting off one foot."
Footwork does not garner much attention compared to a sizzling serve or ferocious forehand, except when players have exceptional movement, either good or bad. French legend Suzanne Lenglen dazzled spectators with her balletic movements in the 1920s, Brazil's Maria Bueno and Australian Evonne Goolagong-Cawley were known for their feline-like grace, and German Steffi Graf for her nimble feet in running round her backhand to hit off her stronger forehand flank. Today, Swiss great Roger Federer shows imperious court coverage, as does scrambling Australian Lleyton Hewitt.
On the other, flatter foot, towering Lindsay Davenport and Maria Sharapova have done their utmost to compensate for their exceptional height by working on their footwork (the 1.87 meter Sharapova once described her slip-sliding performance on clay in Paris as akin to "a cow on ice").
Professional tennis players have nutritionists, fitness coaches and, sometimes, sports psychologists to help them prepare for the on-court challenge. Bailey notes that the element of footwork and movement is often overlooked, from club hacks trying to perfect their game to the pros striving to move up the rankings, despite its importance in a player's performance.
"It's especially true when the game has got faster. A lot of players can't move fast enough to keep up because they don't have the footwork technique to be in position for the next ball."
Bailey grew up in the sport, with his father good enough to compete at Wimbledon (he is still winning age-group titles in his 80s). He got a nursing degree and decided to use his medical knowledge in physical education, with a focus on fitness in tennis, instead of going into the more competitive coaching sphere.
He taught in the US, including at the Evert Academy in Boca Raton, Florida, but a return to his homeland after a divorce led him to rethink his career. It was then that he came up with the idea to concentrate on combining footwork, movement and fitness.
"As a fitness coach, you have to improve what the athlete has, and it makes the most sense to do that with movement, because you have to move to hit the ball," he says.
"It's also better in the economic sense, because I not only can teach it to individuals, but also to groups, and at most you have an hour to work with them."
He pored over thousands of videos of top players of recent years. He pinpointed reactions and responses, devising terms - the Front Foot Hop, the Mogul Move, the Closed Pivot, among others - that can be conveyed to other players in better understanding the game. He says he wants to create a new "language" in teaching tennis.
"Nobody had come up with a full strategic method, it was always about technique. With this you know to do this or that. When you know the moves, I can just tell the player to move back and do a hop, or front spin, or lift their knee up to put more spin on the ball. I use videos, because you can watch it and slow it down, see how the moves are done. Forty years ago you couldn't do that."
Among the players Bailey has helped include British number one Anne Keothavong and Australian Jarmila Gadjosova (in his 25-year fitness career, he also has worked with Monica Seles, Vince Spadea and Jelena Dokic).
"It's been such a confidence booster and so great for my mind as well," Gadjosova says in a testimonial for Bailey's teachings. "Now I feel so much more confident and faster on the court and I cope so much better with everything."
Bailey argues that talent can only take a player so far.
"The really top players always have a team to help them rise to the next level, to get that little bit better. And they need someone to come in and help them polish their footwork, if you really just work on your footwork, then mentally you'll play better. It's like taking a math test; if you've studied really hard, you look forward to it. Movement is all about feeling, reacting, exploding, wanting to chase the ball, and if you get tired you're not going to move as well."
He says women players are easier to coach, because "they're more open minded, while guys are just about getting out and hitting". But he has found there is one thing that unites all the legends in their quest to be the best in the sport.
"The great players are always students, they want to learn," he says.