Just two days after turning 18, the Anglo-Chinese Junior College (ACJC) student completed IRONMAN Tallinn in 12:38:24 – surpassing a record set by his father, Trevor Xie, more than a quarter of a century ago.
At 18 years and two days old, most teenagers are only beginning to figure out what adulthood looks like. Xie Ze Kai marked his arrival by swimming 3.8km, cycling 180km and running a full marathon.
The Singaporean student-athlete completed IRONMAN Tallinn in Estonia on Saturday (22 August), crossing the finish line in 12 hours, 38 minutes and 24 seconds to become the youngest Singaporean to complete a full-distance IRONMAN.
In doing so, he also surpassed a mark that had stood for 26 years – one set by his own father.
His father, Trevor Xie, completed his first IRONMAN in 2000 when he was 18 years and five months old. More than a quarter of a century later, his son followed him across an IRONMAN finish line at an even younger age.
And perhaps most remarkably, Tallinn was Ze Kai’s first full-distance IRONMAN. “It was definitely the hardest race I have ever done,” he told Baseline.
Inspired by Dad, but finding his own way into triathlon
Xie’s journey into multisport is a relatively recent one.
The JC2 student at ACJC has always been active and is captain of the school’s squash team, which claimed silver at the 2026 National School Games A Division competition.
But over the past year, another sport began demanding more of his attention.
“I started getting more serious about triathlon over the past year,” Xie said. “I have always been quite active and I play squash for my school, but triathlon was something different and I enjoyed the challenge of having to get better at three different sports.”
There was also an influence much closer to home.
“My dad also did an Ironman when he was 18, so I grew up knowing about it,” he added. “Eventually I thought it would be quite cool if I could do one too.”
Xie started with shorter-distance triathlons in Singapore, initially approaching the races simply as a way to see how he would fare when swimming, cycling and running were put together.
“Racing swim-bike-run is very different from training each sport separately,” he said. “I enjoyed it and that made me want to see how far I could take it.”
He gradually stepped up the distances, eventually completing the Desaru 113, but the full IRONMAN remained unexplored territory.
Until Tallinn.
Chasing a record that came with a finish
The decision to race in Estonia was not entirely coincidental. Xie would turn 18 on 20 August, just two days before IRONMAN Tallinn.
The Xie family realised that if he could complete the race, he would be younger than the elder Xie had been when he finished his first IRONMAN 26 years earlier.
“The timing worked because I would turn 18 just before the race, and my dad had completed an Ironman when he was 18 years and five months old,” Xie explained.
“We realised that if I could finish Tallinn, I would be younger than Dad was when he did his. That gave me something quite special to aim for.”
But once the entry was confirmed, thoughts of records quickly gave way to a much more fundamental question: Could an 18-year-old attempting his first full IRONMAN actually make it through 226km?
“After signing up, the main goal became just making sure I could actually finish an Ironman,” he said.
Training for an IRONMAN, while preparing for A-levels
For several months, Xie’s life became a juggling act between school, squash and endurance training.
A typical week involved sessions across all three disciplines, sometimes with two workouts in a single day, while weekends were reserved for the longer rides and runs required to prepare his body for what could be more than half a day of continuous racing.
There was no escaping the fatigue. “I also had to balance it with school and squash, so there were definitely days when I was quite tired,” he said.
As Tallinn approached, his training increasingly shifted towards endurance and preparing his body to keep moving for the entire distance. Still, there was one thing training could not tell him.
Having never raced a full IRONMAN before, Xie had no idea exactly what would happen to his body deep into the race.
“Before this I had done shorter triathlons and the Desaru 113, but I had never done the full 3.8km swim, 180km bike and 42.2km run,” he said. “So I didn’t really know exactly how my body would react after so many hours.”
That uncertainty also shaped his race strategy. There would be no ambitious time target.
“Honestly, the main goal was to finish,” he said. “It was my first full Ironman and I didn’t want to chase a timing and end up blowing up halfway. “I knew that if I finished, the record would come with it, so I just wanted to race sensibly, keep moving and get to the finish line.”
226km and one very long day
Race day began with the 3.8km swim, before Xie headed out onto the 180km cycling course through Tallinn and the surrounding Harjumaa countryside.
“The swim went okay and I was happy just to get through it and onto the bike,” he recalled. The bike would account for the largest portion of his day, but Xie knew that going too hard could come at a brutal cost later.
“The 180km bike was the longest part and I knew I had to control myself because there was still a marathon afterwards.” And then came the run.
After already swimming 3.8km and cycling 180km, Xie still had 42.2km on foot between him and the finish line, and by then, the accumulated hours of racing were taking their toll.
“By the run, I was definitely feeling everything,” he said. “There were difficult moments where I was tired and hurting, but at that stage I just kept telling myself to keep moving forward.” Eventually, the calculations began to change.
The finish was no longer something Xie was simply hoping to reach. He realised he was going to make it. “Once I knew I was getting close to the finish, it became much easier mentally because I knew I was actually going to make it.”
12 hours, 38 minutes and 24 seconds after he began, Xie crossed the line.
“Crossing the finish line was a huge relief,” he said. “I was obviously very tired, but I was also really happy because so much training had gone into that one day. “It was quite surreal knowing that I had actually finished a full Ironman at 18.”
And waiting to watch him do it was the man whose footsteps had helped bring him there in the first place.
Twenty-six years later, the roles were reversed
In 2000, Trevor was the 18-year-old crossing his first IRONMAN finish line. “Twenty-six years ago, I was the 18-year-old crossing an IRONMAN finish line,” the elder Xie said. “This time I was standing on the other side watching my son do it.
“Records are eventually meant to be broken. I couldn’t have imagined a better person to break mine. What makes me proudest isn’t his age or the record,” he said. “It’s that he chose something extraordinarily difficult, prepared for it, suffered through it and finished it.”
Xie felt the significance of having his father there too. “Breaking my dad’s record made it even more special, especially because he was there to watch me finish,” he said.
It gives the Xie family an unusual sporting connection spanning more than a quarter of a century: father and son, both completing their first full IRONMAN at 18.
From IRONMAN to A-levels
So what does an 18-year-old do after completing 226km and becoming Singapore’s youngest full IRONMAN finisher? Go back to school.
“Right after finishing, I wasn’t exactly thinking about doing another one!” Xie admitted.
A little recovery, however, has already started changing his mind. “I enjoyed the whole process and I think there are many things I could improve if I raced another Ironman,” he said.
That will have to wait.
For now, Xie has another endurance test ahead of him; albeit one that does not involve a wetsuit, bicycle or running shoes. “I have to focus on my A-levels,” he said. “After that, I’ll see what the next challenge is.”
