Naomi Osaka became Japan’s first ever Grand Slam champion after she thumped a raging Serena Williams 6-2 6-4 in a controversial U.S. Open final on Saturday.

That made the American to be suffering a meltdown after being handed a game penalty.

With Osaka in control of the match, chair umpire Carlos Ramos sent Williams into a rage when he handed the 23-time Grand Slam champion a game penalty for a string of bad behaviour.

The behaviours included a coaching violation and verbal and racket abuse.

Williams then launched a verbal attack on Ramos, demanding everything from an apology to accusing him of being a thief.

The game penalty put Osaka 5-3 up in second set and the 20-year-old Japanese kept her cool to pull off a historic win. (Reuters/NAN)