Line up 20 strands of human hair side by side, with absolutely no space between them. That is about the diameter of the bull's eye that air rifle shooters Martina Veloso and Muhamad Irwan spend much of their waking lives contemplating.
Yesterday, at Palembang's Jakabaring International Shooting Range, the difference between a heartbreaking 10m mixed team qualification stage exit and a shot at Asian Games glory was a score of 0.1, or two strands of hair.
Veloso and Irwan shot a combined score of 829.7 to finish sixth, narrowly behind Chinese Taipei (829.8). Only the top five qualifiers entered the final.
Veloso, 18, blamed the performance on opening-day nerves, as did Teh Xiu Hong who, with 10m air pistol mixed team partner Gai Bin, also did not make their final.
"I cried after the competition, thinking about what if I had done things better, if I didn't feel so nervous. We were so close," said Veloso, who won two Commonwealth Games golds in April.
Against Asia's best, the room for error is tiny, and one wrong decision can scupper years of hard graft. Ask Joan Poh.
She adopted a conservative approach after watching rowers in races prior to her women's single scull event struggle with rough conditions. And it put her on the back foot from the get-go, clocking a time of 9min 48.40sec in the 2,000m heats, more than two minutes off her personal best.
She ended ninth but will return for tomorrow's repechage, to battle for the other four spots in the final.
It was a similar story in Jakarta, with the Republic's swimmers battling the clock, opponents and also their nervous selves.
Games debutant Ong Jung Yi, who finished 12th out of 19 competitors in the 200m butterfly in 1min 59.76sec, said he felt "a bit tired" towards the end of the race.
The 17-year-old added: "I think it's partly because of my sleep - I woke up a few times (last night) but overall I enjoyed the experience."
The quartet who swam the heats of the women's 4x100m freestyle relay - Quah Jing Wen, Marina Chan, Cherlyn Yeoh and Amanda Lim - were also "super nervous", said anchor Lim. But the women regrouped, doing well enough to finish fourth in last night's final and set a national record too.
It is a lesson well learnt - by all.
Poh wore a determined look during her warm-down, going faster than others out on the water with her, breaking the race down in her head as she went.
"The standard (at the Games) is high, but it's still easy to be disheartened. That's why I warmed down like that - I wanted to nail every other process of mine, to put myself in a better mental state. And to learn from what happened," said the 27-year-old.
The margins are small at the Asiad - sometimes as slender as two strands of hair - and there is much to fight for. Which is why Team Singapore are looking at getting back to basics.
"It's good to get the nerves out of the way," said Veloso. "After lunch, we will put this aside, and focus on what we can control - our pre-event training and processes."
• Additional reporting by Nicole Chia