(Reuters) - The International Tennis Federation (ITF) has given its backing to Portuguese chair umpire Carlos Ramos who Serena Williams branded a “liar” and a “thief” during her U.S. Open final defeat by Japan’s Naomi Osaka on Saturday.

Sept 8, 2018; New York, NY, USA; Serena Williams of the USA argues with chair umpire Carlos Ramos while playing Naomi Osaka of Japan in the women’s final on day thirteen of the 2018 U.S. Open tennis tournament at USTA Billie Jean King National Tennis Center. Mandatory Credit: Robert Deutsch-USA TODAY Sports

Williams, who was seeking a record-equaling 24th Grand Slam singles title, was given a warning for a coaching violation before incurring a point penalty for smashing her racket. After accusing Ramos of being “a thief for stealing a point from me”, she was docked a game.

The six-times U.S. Open champion, who eventually lost the match 6-2 6-4 was fined $17,000 by the United States Tennis Association (USTA) for her outburst.

“Carlos Ramos is one of the most experienced and respected umpires in tennis. Mr. Ramos’ decisions were in accordance with the relevant rules and were reaffirmed by the U.S. Open’s decision to fine Serena Williams for the three offences,” the ITF said in a statement on Monday.

Ramos, 47, is the only active tennis umpire to have officiated the men’s singles finals at all four Grand Slams. He has also been on the chair for the women’s singles finals at three of the four majors - the French Open in 2005, Wimbledon in 2008 and at Flushing Meadows on Saturday.

He received praise from the ITF for his professionalism in one of the most controversial Grand Slam finals of all time.

“It is understandable that this high profile and regrettable incident should provoke debate,” the ITF added.

“At the same time, it is important to remember that Mr. Ramos undertook his duties as an official according to the relevant rule book and acted at all times with professionalism and integrity.”

The ITF’s support for Ramos comes after the Women’s Tennis Association (WTA) expressed disappointment over the handling of the match and the USTA’s plans to review of its communication policies after a string of umpiring controversies.

Williams’ behavior in the final has divided the fraternity.

Tennis great Billie Jean King backed the American but Margaret Court, whose major wins record Williams was trying to equal on Saturday, expressed little sympathy for the 36-year-old.