Sisters' rivalry for SEA Games windsurfing spot
Sisters Nicole and Ynez battle for one women's windsurfing spot at this year's SEA Games
They are "super close" and even used to share a room.
But the kinship will have to take a backseat when windsurfing sisters Nicole and Ynez Lim step into the water.
Over the next couple of months, they will be vying for the solitary women's RS:One slot for Singapore at the South-east Asia (SEA) Games in Malaysia in August.
The selection process for the windsurfers started this week with the Singapore Open Windsurfing Championship - which ends tomorrow - and will end in March after two more events.
Ynez, 18, said: "We have been 'fighting' with each other for so many years, since we started out sailing together; we are immune to it already.
"But we are kind of scared of each other in the water because we know each other's strengths and weaknesses well."
Nicole, 20, said: "When I was younger, I used to be jealous of her if she did better, but I've grown out of it.
When I was younger, I used to be jealous of her if she did better, but I've grown out of it. Nicole Lim
"These days, we would sometimes discuss and evaluate our training sessions when we are on the way home."
The siblings are arguably Singapore's top contenders for the women's RS:One slot, as 2015 RS:X SEA Games champion and 2016 Olympian Audrey Yong is sitting out this year.
Ynez competed in the 2013 SEA Games in Myanmar and the 2014 Nanjing Youth Olympics, while Nicole went through a brief Olympic qualifying campaign in 2015.
Nicole's result at the 2015 World Championship eventually earned Singapore an unused Olympic quota spot last year, which went to Yong as Nicole had already stopped her campaign.
"When I first heard the news, I was super happy for Audrey because she's a senior whom I look up to, and I knew the effort that she put in for the campaign," said Nicole, a second-year Nanyang Technological University engineering undergraduate.
"It was only later that I realised that it was a pity for me to have missed out."
Ynez, the captain of her Institute of Technical Education (ITE) swim team, opted for the sailing selections over a place in the team for the Polytechnic-ITE Games.
She said: "For sailing, there is the chance to represent the country, there was no question there."
After four races, Nicole sits in fifth place, making her the top Singaporean at the Singapore Open Windsurfing Championship with 14 points, while Ynez is seventh with 17 points.
Thai Olympic sailor Siripon Kaewduang Ngam, leads the 12-strong women's fleet with three wins, while her teammate Natthaphong Phonoppharat, who also sailed in Rio last year, leads the men's RS:One fleet.
Siripon, 22, clinched the women's RS:X silver at the 2015 SEA Games, while Natthaphong took the men's RS:X title then.
Both of them are aiming for gold at the SEA Games this year.
Nattaphong, 28, said: "We sailed against very good sailors at the Olympics and learnt a lot from observing their techniques.
"I hope to win gold again at the SEA Games this year."