Allegations this week that tennis authorities failed to deal with widespread match-fixing has rocked the game, following similar allegations that have blighted cricket, football and other sports.
The ubiquity of mobile phones and tablets has helped transform bookmakers from operators of dingy, smoke-filled betting shops into multi-billion dollar de facto tech firms, pouring resources into developing apps and complex algorithms and marketing to younger and broader demographics.
"We're no longer restricted by geography or the limited choices of one betting company. And we have wall-to-wall sport every day of the week from across the globe beamed into our lounge rooms, on our smartphones," said Scott Ferguson, a wagering industry consultant. "Technology is everything."
The greatest danger for mobile gambling to intersect with corruption lies in the ease of fixing a one-on-one sport like tennis, darts or snooker, according to experts and professional gamblers.
Mobile apps that allow in-game betting on individual points or games allow athletes to stealthily manipulate the results and may strike some of them as less unethical as throwing an entire match, said Sally Gainsbury, a senior lecturer at Southern Cross University who has written a book on the subject.
"A PERFECT COMBINATION"
Most major bookmakers operate from small offshore jurisdictions, making accurate predictions of industry worth extremely difficult, said Gainsbury.
"There's a large grey sort of offshore market ... in every country, where it's actually just not possible for the government to regulate these sites that are based in all these tiny remote jurisdictions," she told Reuters.
"So it's difficult to get a really accurate size of how much people are betting because a lot of it is actually illegal."
Patrick Jay, a betting consultant and former sports and football director at Ladbrokes, estimates the global sports betting market is likely worth about $1 trillion a year, having doubled in size in the last five years. He expects it to double again in the next five.
The Australian government, citing a 2015 United Nations conference at which Jay was a speaker, put that figure as high as $3 trillion, of which 90 percent was "illegal" or in contravention of laws regulating gambling in which the bet was placed.
That range of figures, which includes betting on sports from football, cricket and tennis to much less widely followed sports like snooker, darts and table tennis but excludes racing, illustrates the difficulty in accurately valuing the overall market.
"It has grown because of mobile technology. It allows people to place bets anywhere, anytime," Jay told Reuters. "People are also dealing in credit, and therefore accounts are being run all over the world. It has created a perfect combination."
Leading bookmakers including Betfair Group PLC, Ladbrokes PLC, Paddy Power PLC and William Hill PLC did not respond to requests for comment. There have not been any allegations of wrongdoing by the bookmakers in the World Tennis scandal.
Worried about the boom in sports betting and incidents of match fixing, countries like Australia and across the European Union are in the process of reviewing laws that experts like Gainsbury say are "hopelessly outdated".
In Australia, for example, 2001 laws regulating Internet sport betting bar anyone from placing a bet on a sporting event online once it has begun, despite allowing live betting over the phone or at retail bookmakers.
William Hill, an official partner of the Australian Open, has a new "Bet-in-Play" feature for its Australian customers that requires access to a smartphone's microphone while the bet is placed to comply with such laws.
"There's been a lot of stagnation where a lot of countries originally said, 'Well this is illegal, we won't let them do this', but of course with the internet you can't make things illegal and stop people going online," Gainsbury said.
(The story corrects tense of transform in paragraph three)
(Writing by Matt Siegel; Editing by Lincoln Feast)
