Petra Kvitova

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

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...

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