PARIS • Patrick Mouratoglou, the coach at the centre of Serena Williams' infamous US Open final meltdown, has called for on-court coaching to be allowed at all tennis events.

The Frenchman insists that coaching goes on all the time at tournaments and to believe otherwise is "hypocrisy".

"Coaching is a vital component of any sporting performance. Yet banning it almost makes it look as if it had to be hidden or as if it was shameful," he wrote in a Twitter post on Thursday. "Authorising coaching in competition and actually staging it so that the viewers can enjoy it as a show would ensure that it remains pivotal in the sport."

He also said that he could not understand why tennis was "just about the only sport" where coaching was not allowed, citing football, basketball and boxing as high-profile examples, and pointing out that elite cyclists are in radio contact with their advisers during races.

Last month, Williams was warned when Mouratoglou was spotted making signals from the player's box during the US Open final against Japan's Naomi Osaka.

The coach later admitted gesturing to his player from the stands during her match, although Williams insisted that she had not seen the signal and that she had "never cheated in her life".

Williams then carried out a running verbal battle with umpire Carlos Ramos, who eventually penalised her a game.

The American described Ramos as a "liar and a thief" before crashing to defeat at a shell-shocked Flushing Meadows.

At the moment, on-court coaching is allowed only in WTA events but not on the men's ATP Tour or at the four Grand Slams. It is understood that the issue will be discussed on the sidelines of the WTA Finals in Singapore next week.

However, any move to allow it during main-draw matches would need to be agreed upon by the four Grand Slam tournaments. This is likely to be problematic with Wimbledon so far entirely against it.

Meanwhile, the All England Lawn Tennis Club announced that it will introduce tie-breaks in the final set of all events for the first time next year, but only once the score in the deciding set reaches 12-12.

A tie-break is normally played to decide the set when the score reaches 6-6. Until now, the US Open has been the only Grand Slam that uses a tie-break in the fifth set.

"A tie-break at 12-12 strikes an equitable balance between allowing players ample opportunity to complete the match to advantage, while also providing certainty that the match will reach a conclusion in an acceptable timeframe," said club chairman Philip Brook.

AGENCE FRANCE-PRESSE, REUTERS