(Photo: CGTN)

Serena Williams has been fined $17,000 by the US Tennis Association in the wake of her outburst during a controversial US Open final loss to Japan's Naomi Osaka.

The American star was fined for coaching, racket abuse and verbal abuse when she accused umpire Carlos Ramos of being "a thief" during Saturday's stormy final.

Williams was incensed at the coaching violation, although coach Patrick Mouratoglou, sitting in her box, admitted that he was coaching when he moved his hands.

that violation carried a 4,000 US dollar fine, while a second violation for racket abuse – after she smashed her racket after dropping her serve in the fifth game of the second set – cost her $3,000.

The second violation also cost her a point in the match, sparking her renewed verbal attack on Ramos, a code violation which carried a 10,000 US dollar fine.

Her third code violation of the match also cost her a game, putting Osaka on the brink of what would be a 6-2, 6-4 victory that made her the first Japanese player to win a Grand Slam title.