She displayed nerves of steel to win her first Schools National C Division tennis final and played a pivotal role in guiding Raffles Girls' School to their first title since 2014.
But one could be forgiven for not knowing the significance of Charlotte Yeo's victory when she stoically strode towards Singapore Chinese Girls' School's Sarah Chan for a consolation hug before leaving the tennis court to join her boisterous schoolmates.
The celebrations were understandable given RGS had found themselves trailing 2-0 after losing their first two singles events.
In the opening match, Ashley Goh lost to SCGS' Deborah Lim 0-6, 0-6. That deficit was doubled soon after when Khoo An Ying fell 0-6, 2-6 to Lee Yenn.
Despite nursing a wrist injury, Charlotte prevailed 6-2, 6-1 over Sarah to kickstart RGS' comeback. Her schoolmates Victoria Lim and Sarah Wong then combined to beat SCGS' pair of Erica Lim and Jaelyn Lee 6-0, 6-4 , leaving the overall tie tied at 2-2.
The improbable fightback was completed when the RGS duo of Sofia Wong and Joy Nicole Lim beat Lorraine Ng and Leeandra Sinnathuray 6-2, 3-6, 6-1 in the final doubles match, sealing a 3-2 victory at the Kallang Tennis Centre.
Charlotte, 13, said: "I was focused on playing my best, being the best and knowing that everything else will come naturally."
When asked about her expressionless demeanour on court, the Under-16 national youth player said: "I've never really expressed myself since I first started playing at eight. Even when I get good grades, I don't really scream. I am better as a calm player."
Her mother Geraldine added: "Charlotte does not change much even when she wins or loses. She's almost like a robot when she is in her zone.
"She did very well today, and I just want her to celebrate her win in her own way."
RGS' coach Gary Tan attributed Charlotte's success to her sheer determination.
"She's a bit like a CPU, she just needs to get the algorithms right. I just have to give her the big picture and she's able to handle it," he said.
"Off the court, she's fun and jovial but on the court, she's like a machine. It's one of the reasons why she succeeds."
Tan, who has been coaching RGS for seven years, was thrilled with his players' efforts.
He said: "I am super proud that we won back the title. The victory today was a testimony of the toil the team went through and reaped the results of collective belief."
SCGS' Sarah, who will be meeting Charlotte again on Saturday in the Singapore Tennis Association Pesta Sukan Youth U-16 final, said: "It was a tough match, I tried my best but Charlotte played really well. I will be looking to improve a few aspects of my game and hopefully Saturday will be my day."
Correction note: This article has been edited for accuracy.