Sue Barker believes “tennis was the loser” in a controversial US Open final – but said Serena Williams had a point when she criticised the umpire.

A series of incidents, which included the beaten American calling Carlos Ramos a “liar” and a “thief”, saw Williams penalised twice.

Afterwards the American said it was “sexist” to have been penalised a game.

“The umpire was following the rules by the book but Serena has a point,” said BBC Sport tennis presenter Barker.

Williams, who was beaten 6-2 6-4 by Naomi Osaka in New York, was given a code violation for coaching, followed by a penalty point for racquet abuse and finally a game penalty after accusing the umpire of lying.

“I’ve sat courtside watching the men ranting at umpires and they haven’t been given a violation,” added former French Open champion and world number three Barker.

“The fact that it was to be a game violation then robbed the crowd of what potentially could’ve been a third set.”

• Naomi Osaka wins after Serena Williams outburst
• Williams accuses umpire of sexism in final

Williams, who was aiming to equal Margaret Court’s record of 24 Grand Slam singles titles, refused to shake hands with umpire Ramos after the match.

She later accused him of sexism, saying: “He’s never taken a game from a man because they said ‘thief’.”

“Both have a point – Serena saying the male players can say what they want to umpires,” added Barker, who was speaking to BBC Radio 5 live’s Sportsweek programme.

“Earlier in the tournament we saw Alize Cornet being given a code violation for changing her shirt on court and then in the same tournament Mohamed Lahyani gets down from his chair to talk to Nick Kyrgios and persuade him not to give up on a match.

“He [Ramos] was following the rules by the book but sometimes the book has to be rewritten.

“You can’t have one rule for some players and some umpires don’t adhere to it and allow players to get away with things. They’ve just got to be fair to the players.

“Tennis was the loser and we lost what was potentially a fantastic match.

“I’ve never seen anything like it since I have been watching tennis. It was sad for the game.”

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What happened?

Williams was given a first code violation after Ramos judged a gesture from coach Patrick Mouratoglou to be coaching.

She said she had not received any tactics from Mouratoglou, telling the umpire she would “never cheat to win and would rather lose”.

The Frenchman later admitted that he had been coaching from the box but that Williams had not seen him doing so.

Williams then received another code violation for a racquet smash at 3-2 in the second set, leading to Ramos docking her a point.

With Osaka leading 4-3, Williams told the umpire: “You are a liar. You will never be on a court of mine as long as you live. When are you going to give me my apology? Say you are sorry.”

That led to Ramos docking her the next game to leave Osaka just one game away from victory at 5-3 up.

Williams refused to take to the court and demanded an intervention from the tournament referee.

Eventually she returned to the baseline, serving out a game to love before Osaka held serve to win her first Grand Slam win.

In her post-match news conference Williams said she was she “was not being coached” and that she “did not understand” why Mouratoglou would say he was doing so.

American 12-time Grand Slam singles champion Bille Jean King, one of the founders of the Women’s Tennis Association (WTA), backed Williams, saying: “When a woman is emotional, she’s ‘hysterical’ and she’s penalised for it. When a man does the same, he’s ‘outspoken’ and there are no repercussions.

“Thank you, Serena Williams, for calling out this double standard. More voices are needed to do the same.”

‘I feel so sorry for Naomi Osaka’

At the end of the match, security staff ran on to the perimeter of the court as Ramos walked off and the Portuguese did not return, as he would usually have done, for the trophy presentation.

Osaka, who describes Williams as her idol, pulled her visor down over her eyes to hide her tears when there was booing from the 24,000 crowd in the Arthur Ashe Stadium prior to the Japanese player being given the trophy.

The jeers were not aimed at her, with the fans instead expressing a sense of injustice at the way home favourite Williams had been treated.

The American appealed for calm in her runners-up speech, asking her supporters to “give credit” to Osaka’s achievement, and the winner was then applauded.

“I’m immensely disappointed,” said Barker. “I was so looking forward to what was going to be a fantastic finale to what has been an incredible tournament and it was all just taken away by Serena and the umpire. I feel so sorry for Naomi Osaka.

“Her first Grand Slam win has been marred in some way. She couldn’t celebrate in the way she wanted to.

“She is one of the most exciting players on the tour. It was just so sad for me to see at the presentation that she was in tears. They weren’t tears of joy.

“The crowd was booing and this was her moment. That’s not the way you want to celebrate your first Grand Slam victory and it was just sad for the sport to see it.”

What are the rules?

According to ITF Grand Slam rules:

• Verbal abuse is defined as a statement about an official, opponent, sponsor, spectator or other person that implies dishonesty or is derogatory, insulting or otherwise.

• Abuse of racquets or equipment is defined as intentionally, dangerously and violently destroying or damaging racquets.

• Players shall not receive coaching during a match (including the warm-up). Communications of any kind, audible or visible, between a player and a coach may be construed as coaching.

Should they be changed?

“It’s weird in the women’s game where they have coaching,” said Barker.

“For all the tournaments, bar the Grand Slams, coaches can come onto the court at the change of ends to speak to their players.

“I was against that. It’s a gladiatorial sport, it’s one against one – you work out how to do it.

“But, if it’s coming to things like this, it is ruining the game and it was just such a disappointing way for the tournament to end.

“If they can’t adhere to the rules then they will have to allow the coaching because we can’t have things like this outburst anymore. It is not good for the game.”

She added: “There can’t be a grey area any more. Maybe there has to be a supervisor that comes on and has the final say before you give a game away.”