Angela Lee had just survived a brutal rematch against Mei Yamaguchi to retain her One Championship atomweight (52.2kg) belt, winning by unanimous decision.
But instead of the riotous joy that followed her previous win over Yamaguchi in 2016 to clinch the title, Lee's mind appeared to be elsewhere on Friday night.
Her first words after being announced the winner came close to a rebuke for the capacity crowd at the 12,000-seat Indoor Stadium.
"Tonight was a huge night for my family regardless of the outcome. You guys don't realise how tough it is to be inside this ring and do what we do," said the 21-year-old while struggling to compose herself.
"I couldn't get the finish tonight because Mei is such a tough opponent and so incredibly skilled.
"And for the two men who were fighting for the featherweight title, I just want to say congratulations... Man, you guys are a tough crowd and sometimes you've got to respect the athletes."
The American, who fights under the Singapore flag, had earlier been in the corner for her younger brother Christian's fight against featherweight (70kg) champion Martin Nguyen, which the latter won by split decision.
TRY STEPPING INTO OUR SHOES
Tonight was a huge night for my family regardless of the outcome. You guys don't realise how tough it is to be inside this ring and do what we do... sometimes you've got to respect the athletes.
ANGELA LEE, after the crowd booed her brother Christian Lee and Martin Nguyen for their ultra-conservative tactics.
It was a contest punctuated by boos from the disgruntled crowd as both fighters spent the bulk of five rounds circling each other warily. Each was issued a yellow card for not engaging by the referee.
The crowd's impatience and hostility did Lee no favours; she was seen in tears just before stepping into the cage for her fight.
She started off sharply enough, capping off the third round by putting Yamaguchi in a rear naked choke and raining blows down before the bell sounded.
But the 35-year-old Japanese had the stronger finish, scoring a knockdown in the final round by connecting with a left foot.
In her first fight since a serious car accident last November, Lee then had to defend doggedly to get across the line. With the victory, Lee improved her record to a perfect nine wins from nine fights.
Yamaguchi, who also lost by a unanimous decision in 2016, felt she had done enough to claim the belt. Asked if she thought Lee had put in a weaker performance this time, she said: "Yes, I felt that too. Maybe she was having a hard time cutting weight.
"Our strategy was to not go too strong in the early rounds and get the points in the last two rounds and I thought that worked out. But the decision went her way."
Both Lee siblings did not speak to the media after the event, with only Nguyen and Yamaguchi returning to the cage for interviews.
Nguyen apologised to the crowd immediately but the Australian was diplomatic when asked what his take was on being in a title fight in which his opponent refused to engage him. He said: "Look, props to Christian. No matter what, as Angela said, it is really hard being in here. It's hard to please the crowd."