She thought she had given her all in the heats yesterday morning, when she established a new national Under-14 record in the women's 400 metres freestyle.
So when Gan Ching Hwee clocked 4min 19.61sec in the event's final at the China Life Singapore National Age-Group (Senior) Swimming Championships at the OCBC Aquatic Centre yesterday, the result surprised the Chinese Swimming Club (CSC) swimmer and her coach Eugene Chia.
The winning time beat her 4:22.76 effort in the morning, which erased Quah Ting Wen's previous age-group national mark of 4:24.73 set at the South-east Asia (SEA) Games in 2005.
The 13-year-old's evening swim yesterday also beat the 2017 SEA Games qualifying mark of 4:20.20, meaning she will make her SEA Games debut in August in Kuala Lumpur, subject to approval by the Singapore National Olympic Council (SNOC).
"I am quite happy with my swim because I was really nervous at the start," said Ching Hwee, a Year 2 student at Methodist Girls' School.
"I was wondering if I could better my time from the heats because I went 100 per cent in the morning."
CSC head coach-designate Chia said: "We have been aiming for the SEA Games, but this was actually not one of the events we were looking at.
"Her timings are actually much closer in two other events - the 400m IM (individual medley and 800m free - so this is a very good surprise."
Three other swimmers also made the 2017 SEA Games qualifying marks yesterday.
Francis Fong of Swimfast Aquatic Club (SAC) clocked 55.85sec in the men's 100m back to surpass the qualifying mark of 56.31, while his clubmate Christie Chue bettered the women's 100m breaststroke SEA Games standard of 1:11.87 with a 1:11.77 swim.
Subject to SNOC approval, Francis, 17, will also make his SEA Games bow in Malaysia, while Christie, also 17, will swim in her second Games this year.
In addition, freestyle specialist Danny Yeo made the cut for the biennial Games yesterday, clocking 1:50.48 in the men's 200m freestyle heats yesterday morning, and 1:49.37 last evening. Both efforts cleared the SEA Games qualifying mark of 1:50.73.
"It was a very good swim, it was a PB (personal best) and I have not come close to this time since the last SEA Games," said the 27-year-old Aquatic Performance Swim Club athlete, who had suffered from dengue and injuries over the last two years.
Yeo finished second to Malaysia's Welson Sim (1:49.27), who won the bronze in this event at the 2015 SEA Games, and qualified for the Rio Olympics in the men's 400m free last year.
Yeo said: "It's very heartening... Being able to keep pace with him at this point of the season is pretty good for me as well."
National Training Centre head coach Gary Tan was pleased with the local swimmers' showing yesterday.
He said: "The good thing is that there's quite a big depth (of swimmers) coming along.
"It's good that the clubs are doing a really good job with developing some of these youngsters coming through.
"But I am most satisfied with someone like Danny, who hasn't had a PB for a long time, to come in with a PB and feeling pumped and ready to swim.
"It bodes well for the men's 4x200m free relay team, not just for this SEA Games, but also the Asian Games next year as well."
The meet continues today and ends on Sunday.
Gan Ching Hwee's winning time in the 400m free final surpasses the 2017 SEA Games qualifying mark of 4:20.20.
This article was first published on March 15, 2017.
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