She towers above him, but she can't do without him -- so much so they even email each other up to 75 times a day.
From the time they met 15 years ago, Maria Sharapova has been able to count on a man who has masterminded her rise to becoming the world's highest-paid female athlete.
"He knows everything that's going on. He knows where I'm going to be tomorrow, he knows where I am now," she told CNN's Open Court show.
"He" is Max Eisenbud, who first met the Russian when she was a 12-year-old tennis hopeful working with renowned coach Nick Bollettieri in Florida.
Then Eisenbud had a low-paying job liaising with young players' parents at the Bradenton academy that IMG bought off Bollettieri, but now he's Vice President of Tennis at the world's leading sports agency -- having made a fortune not only for Sharapova but also China's most bankable tennis star, Li Na, the No. 2 earner on Forbes' 2012 female athlete list.
"As an agent you just get lucky sometimes, and I'm just a really lucky guy," said the 41-year-old agent.
"I just really try not to mess it up!"
His lucky day came on July 3, 2004 when the 17-year-old Sharapova stunned Serena Williams -- and the tennis world -- in the Wimbledon final to win her first grand slam title.
With her model looks and youthful charm, blue-chip sponsors fell over themselves to get a piece of the action. Forbes magazine reported that Sharapova earned almost $28 million in the year up until June 2012 -- $22 million of that was from endorsements.
They might make something of an odd duo, with the glamorous Sharapova standing at 6 foot 2 inches and Eisenbud, a short, balding man from New Jersey, but as a business partnership they have the perfect synergy.
"We've just been very open and honest and real, and he's someone who says it like it is," said Sharapova, who like Eisenbud was born in April -- but 15 years apart.
"I think that's one of the greatest things that I appreciate in people, and he's done that from the very beginning. He understood the dynamic of me being the athlete, of working for me.
"Agents have much bigger jobs than just everyday life -- booking planes, looking into your agenda -- of course he's trying to make you money and make you big deals, but at the end of the day, he does everything for me.
"He has this old-fashioned calendar and just looks at every date. He knows my schedule, exactly when I'm flying to this tournament, when I'll be back, when we can fit this in.
"He knows my training hours so there are some things that I prioritize over others, and there are certainly some shoots creatively that I would like to do and he's like, 'We just don't have time for it', so I have to ax that out, but we usually agree on many things."
While Sharapova is comfortable on the red carpet and at celebrity parties, her manager is happier making deals.
"He's constantly looking at his BlackBerry ... if you need to get his attention, you should probably send him an email. That's the way I see our relationship," she said.
"He's very good at some things; others he's just absolutely hopeless at, like if you go to an event and you're on the red carpet, he has no idea what's going on.
"He's like 'Hey' and he's talking to all these people and you're like, 'OK, where am I going? Am I doing interviews? Or a step and repeat? What's going on?'