Serena Williams' coach at centre of fresh US Open controversy

One year after sparking the coaching violation that started Serena Williams’ infamous meltdown in the 2018 US Open final, Patrick Mouratoglou has caused a stir again.

Serena’s coach was in Stefanos Tsitsipas’ box during his shock loss to Andrey Rublev in New York on Tuesday.

The Frenchman is Serena’s full-time coach but also helps out Tsitsipas - as we saw at the Australian Open in January.

And with Mouratoglou watching on from his box on Tuesday, Tsitsipas was hit with a coaching violation of his own.

While it wasn’t immediately clear whether Mouratoglou or Tsitsipas’ father was to blame, many tennis pundits and fans couldn’t help but point the finger.

Tsitsipas melts down

The eighth-seed crashed out of the US Open having unleashed a tirade against the chair umpire, who he called a "weirdo."

World No.43 Rublev, who two weeks ago earned the biggest win of his career when he beat Roger Federer in the third round at Cincinnati, attacked Tsitsipas with a barrage of forehands and broke his opponent five times in the 6-4 6-7 (7-5) 7-6 (9-7) 7-5 win.

But Tsitsipas, whose best showing at a grand slam came this year in Australia where he reached the semi-finals, received a coaching warning early in the third set at Louis Armstrong Stadium.

The Greek, one game after receiving a time violation in the fourth set, then became furious when the umpire would not allow him extra time on the changeover to change his bandana.

An angry Tsitsipas told the umpire: "You're a weirdo, you're all weirdos."

He also asked to be given a point penalty, which the umpire granted at 3-4 before Rublev went on to hold to love.

Tsitsipas has now endured consecutive first-round exits at grand slams following his early departure from Wimbledon.

Up next for Rublev, who reached the US open quarter-finals in 2017, will be either Frenchman Gilles Simon or American wildcard Bjorn Fratangelo.

with AAP