They each weigh 71kg, are two centimetres apart in height and look almost identical.
When national divers Timothy and Mark Lee were asked how others tell them apart, they looked at each other and chorused in perfect unison: "Mark has no mark."
Pointing to the right side of his face by way of explanation, Timothy, who is two minutes older, said: "I have a mole on my face and Mark doesn't."
The 20-year-old twins can easily finish each other's sentences and their minds appear to be in perfect sync - the same way their bodies will have to be when they compete in the men's 3m synchronised platform event during the 28th South-east Asia (SEA) Games in Singapore from June 5 to 16.
The duo, who will be assessed based on the similarity and co-ordination of their movements during their event, reckon their identical build and natural chemistry translate into smoother rehearsals.
Speaking to The New Paper before their training session at the OCBC Aquatic Centre, Timothy said: "I think being of the same height and weight help with how hard we press the board.
"When we walk down the board, I can somewhat feel Mark moving, so I pace myself accordingly.
"But I don't know if that's because we're twins or we've been doing synchro for a long time."
Mark added: "We've seen some other teams having to practise a lot together just to get their rhythm right.
"But for Tim and I, it comes quite naturally and we don't need to do anything extra."
The twins had won the silver medal in the same event at the 2013 SEA Games in Myanmar and are looking to go one step further this year.
Naming Malaysia, who had won the gold in 2013, as their toughest opponents, Timothy said: "It won't be easy.
"But anything can happen in competition, so we're just going to do our best."
The brothers are familiar with their Malaysian rivals, having taken part in many competitions together.
"It's a love-hate relationship," said Mark.
"But it's nothing personal, just business."
Timothy, who was "ping-pong buddies" with Malaysian diver Ooi Tze Liang during the Youth Olympic Games, said: "When we're training with them we're good friends but, during the competition, we will all have our game faces on.
"Once the competition's over, we'll then say 'good job' and high-five one another."
Mark and Timothy will also be competing in the men's 3m individual event, but insist there is no rivalry between them.
"When we compete in individual events, we are always competing against ourselves," said Timothy.
"There's no use thinking about the competition."
Mark, who had ended the nation's 28-year SEA Games diving medal drought with a silver in the 3m individual event two years ago, agreed, saying: "That's what works for us."
The Republic Polytechnic graduate had missed out on last year's Asian Games due to an injury, and is raring to go all out at this year's Games.
"The injury was a big blow to me," he said.
"And coming from that, I'm just so ready to do my best at the SEA Games."
Having seen and experienced first-hand how the backing of a vocal partisan home crowd aided their Australian rivals' cause at the 2012 Fina World Junior Diving Championships in Adelaide, the twins are hoping for the same strong support when they compete at the OCBC Aquatic Centre next month.
"When we were in Australia for the World Juniors, the whole stadium just roared for their own divers and I really felt the pressure then" said Mark.
"That's when I understood the importance of crowd advantage."
Timothy, who had experienced his first taste of home crowd support five years ago at the inaugural Youth Olympic Games here, added: "There's nothing better than coming out of the water and hearing the crowd cheer for you, whether it's a good or bad dive.
This article was first published on May 24, 2015.
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