For seven months, they slogged under the hot sun, scurrying around the courts at the Kallang Tennis Centre readying themselves for their big day at the BNP Paribas WTA Finals.
When the event came, they strode onto centre court, warmed up and ready for action - except they were not wielding rackets.
Meet the tournament's 30 ball kids - tasked with supplying Serena Williams the ammunition for her bazooka-like serves and giving Maria Sharapova a towel to dry herself after yet another marathon match.
Said Nathalie Tan, 15: "We have trained hard since March for this.
"But it was worth it because I got to see my idols up close."
The CHIJ Secondary (Toa Payoh) student, who is a big fan of world No. 5 Eugenie Bouchard, added: "We didn't talk much to them but that's normal because they are very focused on court and we had to be professional as well."
The ball kids were chosen after a rigorous process under the Singapore Ballkids Programme, a joint initiative by national agency Sport Singapore and Singapore Tennis Association.
From a pool of 72 children, aged 13 to 16, the numbers were whittled down to 30.
They were coached and assessed by Darren Sturgess and Matthew Dutton, trainers from Tennis Australia.
They got up to speed on the responsibilities of a ball kid through on-the-job-training.
While two kids played a match, the rest would be on the sidelines, ready to retrieve the balls.
While that may seem a simple task, they found out that they had to observe very carefully the players' habits to ensure smooth play on the court.
Nathalie, who has played tennis since she was seven, said: "At first, there were jitters.
"I rolled the ball too quickly at times. But as the tournament went on, it got better and better.
"You also learn about the player's habits, like how Sharapova only likes to get the ball from her right.
"So we must make sure the ball kid on the right has enough balls."
Other notes burned into her memory include her observation that world No. 1 Williams prefers to have just one ball with her during serves.
For fellow ball kid Mark Lim, 13, the experience at the Singapore Indoor Stadium, which has left him thirsting for more, said: "I just imagined I was out on the courts at Kallang Tennis Centre to calm myself down."
The St Patrick's School student added: "I've learnt a lot from looking at their strokes and also how focused they are on the court. "I'll definitely try to sign up for this next year."
This article was first published on Oct 27, 2014.
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