Serena Williams has been criticised by 24-time major champion Margaret Court for her dramatic outburst at the umpire during her US Open final loss to Naomi Osaka.

In incredible scenes at Flushing Meadows on Saturday, Williams, aiming to equal Court's record of grand slam triumphs, received a series of code violations en route to a 6-2 6-4 defeat to her 20-year-old opponent.

Williams initially felt hard done by when handed a first-set warning for what chair official Carlos Ramos believed to be on-court coaching.

The home favourite was then docked a point for racket abuse, having been broken in the second set, subsequently brandishing Ramos a "liar" and a "thief", comments which the umpire deemed to be verbal abuse, warranting a game penalty.

Williams felt she had been treated more harshly than a man would in the same situation, but Court had little sympathy for the 36-year-old.

"We always had to go by the rules," said Court, in quotes reported by The Australian.

"It's sad for the sport when a player tries to become bigger than the rules.

"Because the young player outplayed her in the first set, I think pressure got her more than anything."