Behind the shadowy practice of 'courtsiding' at the US Open

NEW YORK — The arrest of an Estonian man last week for trespassing at the U.S. Open has renewed questions about "courtsiding," the surreptitious collection of instant data for gamblers using online exchanges to bet on all angles of professional tennis matches as they unfold in real time.

A private enforcement team called the Tennis Integrity Unit spotted the man, identified as Rainer Piirimets, in the upper reaches of Arthur Ashe Stadium during a match featuring No. 13 seed Petra Kvitova. Police arrested him on charges he violated a written notice to stay away from the U.S. Open grounds after the unit caught him courtsiding there last year.

The courtsiding suspect wasn't alone: Tennis officials say at least seven other people were kicked out for transmitting results at this year's tournament.

Here's a look at the cat-and-mouse betting game within the game of tennis:

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CATCHING COURTSIDERS

Little is known about the 33-year-old Piirimets or who employed him. Court papers list his address as a Quality Inn in Queens, where attempts to reach him were unsuccessful. And a public defender's office representing him didn't respond to messages seeking information about him.

The integrity unit won't talk about its techniques for catching them. But it's believed they rely on photos of known offenders and can scan the grounds with closed circuit cameras for suspicious activity.

The arrest of a British man named Daniel Dobson at the 2014 Australian Open offered insight into one trick of the trade: Authorities claimed he had a special device concealed in his shorts that allowed him to instantaneously relay the result of each point without looking away from a match in progress.

It's a fun way to make a living, said Brad Hutchins, a former courtsider from Australia and author of "Game Set Cash! Inside the Secret World of International Tennis Trading."

"The job is amazing," he said in an email. "Traveling the world watching live sport is a dream job. We're all aware it skirts a grey area but the trade off of dodging security was worth it."

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Experts say courtsiders are trying to get match data to gamblers so fast that it gives them an edge in contests that let them bet on aspects of a match while it is in progress.

Even though many matches in a tournament are on television, courtsiders try to take advantage of short delays in the live video feeds. They are also trying to enter data on the outcome of points faster than the umpires, who feed them into computers that transmit around the world. Getting the results first, even by a few seconds, can give bettors an edge over others looking at odds based on the previous point.

On betting sites, gamblers place bets on who will win the overall match or individual games. There are also bets on whether the next game will go to deuce, on how many games will be played in a set and on how many games an individual player will win.

Some bets are even placed on the outcome of the next point in an ongong match. For those wagers, one betting site cautions, "You have to move quickly."

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U.S. Open tournament director David Brewer has said banning courtsiders protects the sport's integrity because it's a "logical conclusion" that it could be related to the more serious issue of match-fixing.

"Where there's smoke, there's fire," he said.

But others argue that the activity itself is harmless and that the enforcement has its roots in a decision by the men's and women's tours to sell exclusive rights to their scores to media data firms with clients that include large overseas betting exchanges.

Courtsiding became "a lot more regulated" since tennis made the deal, Hutchins said.

"The fact is obvious to courtsiders that they're protecting their monetary interests over the integrity of the sport because security went through the room after the contract went through," he said.