Tennis has a spectator type its rulebooks do not recognise: someone who buys a ground pass, sits close to a low-numbered court and talks at a player for hours, not to back an opponent but to protect a wager. Jiri Lehecka has described being taunted through three sets on court four at the US Open and asking the chair umpire to step in — only to be told nothing could be done while the man stayed short of insults.
Players say it is now routine rather than rare, and worst where the money is smallest: outside courts, where a handful of voices carry, and the lower-tier World Tennis Tour, where thin crowds make a lone heckler conspicuous. Lorenzo Musetti says it happens far beyond Italy; Leandro Riedi confronted a spectator he believed had backed him to win. The Italian Open and the US Open are the two events players name most often.
The awkward part for the organisers is commercial. On the eve of this year's tournament the US Open announced a partnership with the prediction-market operator Kalshi, then began pushing Kalshi-sponsored match-prediction articles through the tournament's own app. The event now takes revenue from the same activity its players say is following them onto the court.
Operationally there is nothing to enforce. Neither the ATP, the WTA nor the four grand slams carry a rule aimed at disruptive bettors, so an umpire can only act once a spectator becomes abusive — a line experienced hecklers know precisely where to find. That leaves it to the players, who are split. Musetti wants the governing bodies to put security on it; Jakub Mensik and Tommy Paul treat it as part of the job; Coco Gauff simply dares them to try. Lehecka draws the line at intent: "as soon as you start going against the other player … this is wrong."
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Original summary by Proventier.