Last updated on .From the section Tennis

Naomi Osaka (left) did not look like someone who had just won her first Grand Slam title

2018 US Open Venue: Flushing Meadows, New York Dates: 27 August-9 September Coverage: Live radio coverage on BBC Radio 5 live sports extra; live text commentaries on the BBC Sport website

Standing a few feet away from the Grand Slam trophy which she had just won, Naomi Osaka started crying.

The 20-year-old Japanese had just beaten her childhood idol Serena Williams, bidding for a record-equalling 24th Grand Slam title and her first since giving birth, in the US Open final.

Still wearing the black visor she had worn throughout the 6-2 6-4 victory, Osaka - the first player from Japan to win a major tournament - pulled it down over her face to cover the emotion.

During what should have been the happiest moment of her career, they did not seem to be tears of joy.

Boos rang around Arthur Ashe Stadium - not directed towards her, but at a sense of injustice felt by most of the 24,000 crowd against American superstar Williams.

"I felt bad at one point because I'm crying and she's crying. You know, she just won," said former world number one Williams, 36.

Former Wimbledon champion Pat Cash said on BBC Radio 5 live: "This was the most bizarre match and presentation I have ever seen."

So, how did it get to that point?

The expectation

From the moment an image of Williams emerging from the locker room appeared on the big screen there was an expectant, partisan atmosphere inside Ashe.

Serena might be a global superstar but more pertinently she is an American idol: appearing on television commercials, plastered across huge billboards on New York's Fifth Avenue.

Tell anyone you meet in the city that you're here to cover the US Open and it brings up one topic: Serena.

"You've watched Serena? Wow, that's so cool. I'm not really into tennis but I love Serena."

They love her.

So, as her mind started to unravel and the match quickly followed, it was unsurprising to hear the mood of the New York crowd turn.

Code or no code?

Serena Williams called umpire Carlos Ramos a "liar"

Murmurs of dissent were first heard when Williams, who had already lost the first set at Flushing Meadows, was given a code violation at 2-1 in the second after chair umpire Carlos Ramos ruled that her coach Patrick Mouratoglou was signalling tactics from the stands - which is not allowed.

Williams was seriously irked. "We don't have any code," she told the Portuguese. "I don't cheat to win. I'd rather lose."

After the match, Mouratoglou admitted in a television interview he had been coaching - but added "I don't think she looked at me" and "everybody does it".

If the pair do not have a code, as Williams says, and if she did not see him make any signals, then she has a right to feel aggrieved - but with her coach, not the rule book.

The United States Tennis Association, which runs the tournament, issued a statement later on Saturday backing Ramos. It said he acted "in accordance to the rules".

While Williams says she wants to "clarify" what Mouratoglou was thinking and saying, the Frenchman cannot be blamed for her anger escalating.

Did the umpire - or a lack of self-restraint - cost Williams?

Williams smashed her racquet and was docked a point

The Ashe crowd has often sensed when Williams needs their backing the most, with huge roars when she trailed 30-0 on serve at key moments against Karolina Pliskova and Anastasija Sevastova helping her turn those games around on the way to victories earlier in the tournament.

Again they showed their support as Williams, now pumped and finding her shots, broke Osaka's serve for the only time in the match in the fourth game.

But when Williams lost her serve in the following game, the mood changed completely.

First, the American smashed her racquet, and when Ramos gave her another violation - again a correct one - she exploded.

"I didn't get coaching. You need to make an announcement that I don't cheat. You owe me an apology," she told the umpire.

"I have never cheated in my life. I have a daughter and I stand for what's right for her. I have never cheated."

By now Ramos was getting the sort of treatment reserved for a pantomime villain.

Mood turns ugly

Williams argued with the tournament referee

From that point it was a matter of when, not if, Osaka went on to clinch victory.

She broke serve again for a 4-3 lead and then more drama unfolded when Williams continued to rant at Ramos.

"You stole a point from me. You are a thief," the 36-year-old said.

That earned Williams a third violation for verbal abuse, Ramos announcing he had penalised her a game as a sense of confusion and disbelief swept around the stadium.

An emotional Williams remonstrated further with Ramos and called for the tournament referee in what was rapidly becoming a chaotic situation.

Those pantomime boos quickly turned more menacing, however.

Loud jeers rained down on to the court. Some spectators were on their feet, some had their thumbs pointing down, and some shouted abuse at the Portuguese umpire.

Osaka, somehow, maintained her cool.

"I didn't really hear anything because I had my back turned," she said.

Was the umpire right?

Williams was tearful during the exchanges with the umpire

On all three counts, Ramos correctly penalised Williams by the letter of the law.

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.

However, Chris Evert, an 18-time Grand Slam singles champion, said Ramos should have used common sense.

"Because of the big occasion - finals, the score, a game penalty - he should have warned her," the American told BBC Radio 5 live.

"Scold her. 'Ms Williams you need to be quiet because if you keep going on like this it will be a game.'

"Because of the enormity of the moment he should have given her a little bit of a break - but instead he just went right for the jugular."

'Let's not boo any more'

Osaka said she was "sorry the match had to end like this"

Ramos was not the only one going "for the jugular" - so did Osaka.

Although Williams held to love immediately after the game penalty, the Japanese 20th seed maintained the composure she had showed from the start to take her second match point.

That was the moment Osaka, who was brought up in New York after her family moved over from Japan, had dreamed of since picking up a racquet - beating her idol in a Grand Slam final.

"When I hugged Serena at the net I felt like a little kid again," said Osaka, who later revealed she made a school report on Williams in third grade.

Still it felt like it was not the special moment it should have been.

Boos continued to be heard at the end of the match and again when the presentation began.

Osaka began to cry - a heart-wrenching moment which was hard to watch.

That's when Williams, 16 years older than her opponent, intervened as her human and maternal instinct kicked in.

"Let's not boo any more," she pleaded. "Congratulations Naomi. No more booing."

The crowd responded and the jeers turned to cheers as Osaka took the microphone.

"I know everyone was cheering for her and I am sorry it has to end like this," she said.

Humility and a sweet innocence off the court, but explosive hitting and steeliness on it, one imagines Osaka will have more Grand Slam victories to savour in the future.

'A surreal experience' - what they said

BBC tennis correspondent Russell Fuller: "This must be the most surreal experience. A worthy champion but sadly for her it will be remembered for a very, very different story."

Former Wimbledon champion Pat Cash on BBC Radio 5 live: "This was the most bizarre match and presentation I have ever seen."

Former US Open champion Andy Roddick: "Common sense should've prevailed in my opinion. He's within his power to make that call. I've seen an umpire borderline coach a player up, and another dock a game for being called a thief in same tourney. There needs to be some continuity in the future."