Sleep was proving elusive for Yip Pin Xiu the night before her race towards history, bidding to become the first Singaporean to win multiple golds at the same Paralympics.
She went to bed at 9pm, only to find herself drifting in and out of sleep. At the back of her mind, she knew that she had trained hard, but was unsure if that was enough in the 50m backstroke S2 event despite being the world record holder and clear favourite.
A 30-minute delay at the Olympic Aquatics Stadium in Rio due to problems with the water pump only prolonged her nerves ahead of the final on Thursday night (Friday morning, Singapore time).
"I really just wanted to go into the pool," the 24-year-old, who was born with muscular dystrophy, told The Straits Times (ST) afterwards.
When she finally did, wheeled across to lane four by her coach Mick Massey, all that anxiety was released in the water as she stormed to a commanding victory.
Yip clocked 1min 0.33sec, ahead of China's defending champion Feng Yazhu (1:02.66) and Ukrainian Iryna Sotska (1:17.22).
It was Yip's second gold in Brazil - she won the 100m back S2 last week in a world-record time. Her split of 59.38sec in the first lap was also a world record in the 50m back S2. This was her fourth Paralympic medal overall after collecting a gold and silver at Beijing 2008, making her one of Asia's most successful female para-swimmers.
Such was the magnitude of her achievement that a host of politicians, including Prime Minister Lee Hsien Loong and President Tony Tan Keng Yam, lauded her accomplishment on social media.
Yip, the reigning ST Athlete of the Year, said: "When I touched the wall, I was tired and panting a lot, but I didn't know who had won. I couldn't tell when I saw the crowd. I can't see the scoreboard without my glasses either."
Only when she got to the side of the pool and saw a smiling Massey did she know.
Yip's muscle-wasting disease is changing and weakening her body - she takes between 98 and 108 strokes to complete a 50m lap, much more than the 16 or so needed by an Olympic swimmer.
However, her team have repeatedly assured her that she is at her fittest now. To help her swim faster, Massey noted, hours were spent on helping her adopt a flat body position in the water.
"She has to try to swim on top of the water, as close to the surface as possible without dropping her hips.
"When she swims really quickly and is stroking at 65 times per minute, it is difficult for her to stretch her body.
"She can't stretch her legs, so what we do is we try to extend the hip flexors and push the glutes to stay on top of the water. Core work was a huge part in her training."
Yip's success also stems from a steely determination and the knowledge that she swims not only for herself but for a greater cause.
She said: "I don't think any word can describe my emotion. I'm happy about the race, I'm so grateful for the team and for Singaporeans supporting us. The support they have shown us in the past week has been enormous."