To figure out where all this extra money's coming from, leave the grass of Wimbledon behind for a moment and travel across London to the O2 Arena, home of the Barclays ATP World Tour Finals. The clue's in the name. There's a sponsor for the event, another for the match statistics - even the aces are brought to you by Mercedes-Benz.
Revenue from official partners at the ATP (Association of Tennis Professionals), which runs the worldwide men's tour, has increased 215% in six years. Sponsors aren't just splurging for names on billboards either. They're getting involved. There's a fan zone at the O2, where visitors can see how their serves compare with the pros' with Ricoh, watch Tecnifibre restring a racquet or pose for the chance to win goodies from Lacoste.
Tennis has taken entertainment values from entertainment venues, says Robert Datnow of the Sports Consultancy, which worked with the World Tennis Association to place the World Tour Finals' sister event in Istanbul. The event there featured a promotional match on the Bosphorus Bridge, courtesy of city authorities keen to get in on the action. 'The marketplace for eyeballs and filling stadia is more competitive now,' he explains. 'Tennis is competing for an entertainment audience. People are making a decision about whether to watch Strictly Come Dancing or the ATP or WTA finals.'
In the face of this competition, the sport is trying to get fans more involved, whether through sponsors or through a rapidly expanding digital media machine. Page impressions at the WTA Tour Finals site, where you can go behind the scenes with Serena Williams or Ana Ivanovic, increased 127% in only one year.
'In other sports, players are more remote. In tennis, players are made to be much more front and centre,' says Datnow.
Tennis allows a unique intimacy between players and spectators, says Clifford Bloxham of Octagon, a talent agency representing celebrities from footballer Daniel Sturridge and ballerina Darcey Bussell to chef Atul Kochhar. 'Every two games, they sit down in front of the camera and you get to share that moment,' he says. 'In football, you never get that.'
This isn't the only marketing box tennis ticks. It's a global, gladiatorial, year-round game, with natural breaks perfectly suited for commercials and analysis. Bloxham points to the way Baileys was invented by Diageo's marketers, who figured out their ideal drink's characteristics and only then made the product. 'If you were to do that with a sport, you'd end up with tennis. You couldn't do better if you tried.'
Female players are particularly marketable. There are three women in Forbes' list of the most endorsed sport personalities in the world - all are tennis players. Andy Murray has to compete with Lewis Hamilton and Cristiano Ronaldo for sponsorship; Maria Sharapova doesn't.
In common with other sports, tennis is busy capitalising on its previously unrealised commercial potential. Blaring rock, swooping spider cams and the thunderous heartbeats that accompany players' line call challenges at the O2 aren't just signs of fan engagement, they're also testament to a new and deliberate dynamism in tennis marketing.
'We've got to try to attract a younger audience and I don't mean kids of 12,' says ATP president Chris Kermode, who was tournament director at the World Tour Finals when it started in London six years ago. 'There's a huge market of light sports fans in their 20s, who maybe bypassed tennis growing up. We want them to taste it.'
Taste it, they have. Last year, 263,000 people came, making it the fourth biggest annual sport event in the UK. It's hard to escape the fact that the World Tour Finals and much of modern tennis are about as far from Wimbledon whites and strawberries and cream as you can get. 'Reaching through old preconceptions' is how Kermode puts it.
Of course, neither he nor anyone else in tennis has a bad word for Wimbledon, but the sport's dramatic transformation surely has implications for its place as the world's top tournament.
'There's only one Wimbledon and only one Centre Court. That place is hallowed. It's eerie, wonderful and superb,' says commentator and former British number one Andrew Castle. 'But the enemy is complacency. You can't stick around and hope it will continue. You've got to make things happen.
