Novak Djokovic is a lean whippet of a man, Boris Becker was a pit bull. Djokovic once put on a wig for fun and danced in public; Becker rumouredly wore wigs in public so no one could recognise him. Djokovic needs to win the French Open to complete his Grand Slam set; Becker has won 49 titles, none of them on clay.
Welcome to December and the strange tennis marriage. Fortunately, Serb and German are not without similarity: Both are given to theatrical mutterings on court.
This union of legends appears all rather romantic, but intrinsically coaching is a practical exercise which involves the ruthless player constantly asking: What's good for me? And so one day he embraces his coach in public as family, the next day - or after 15 years in David Ferrer's case with Javier Piles - he culls him as inept employee.
It appears harsh yet this is the pull of perfection: Athletes want answers and no one has them all. In time, even the most inspirational tutor can turn into a boring nag. Hell, even Yoda with his backward English - "stopped they must be; on this all depends" - would be kicked out the door.
But Djokovic-Becker is new and we search hard for clues to understand this alliance. Coaching fascinates for it is a throwback to the ancient idea of gurus - except in sport the pupil puts teacher on contract - and deep meaning is looked for in every merging. Surely winning is a science that only few can impart, such as men of high tennis IQ like Mats Wilander.
Not quite. As coach, Wilander won little, while mothers (Melanie Molitor, Martina Hingis' mum) and fathers (Jennifer Capriati's dad, Stefano), some with no grand pedigree in tennis, have coached successfully. Let's not forget uncles called Toni and snoring husbands named Jiang Shan (who coached Li Na).
Coaching is not particle physics clearly. It is also slightly sexist. Most women are coached by men and very few men by women. Neither makes sense. The combative Martina Navratilova could coach anyone, so might the tactical Chris Evert, certainly the adroit Hingis. Reading tennis or unravelling technique are not exclusively male virtues. After all, two women named Gloria and Bertha built a savage male warrior called Jimmy Connors.