Schooling caused a sensation at Rio 2016 when he beat his idol Michael Phelps – who has a record 23 Olympic gold medals – by a fingertip to win the 100m butterfly.

But the city state’s first Olympic champion hasn’t been at his best since, and looks like an outsider to win gold again.

The 26-year-old told Singapore broadcaster CNA that “a lot has happened the past four or five years, and it’s been a rollercoaster ride, it’s been up and down”.

However, he added: “I actually feel less pressure … people just look back to what happened a year ago, two years ago.

“You’re only as good as your last meet.”

“At the end of the day, there’s really no expectations on my shoulders,” he said.

Schooling singled out US star Caeleb Dressel and Hungary’s Kristof Milak as rivals who will be “hard to beat”.

The Singaporean has performed poorly in recent times – he crashed out in the heats of the 100m butterfly at the 2019 world championships in South Korea.

Later that year, he won only one individual title at the Southeast Asian Games in the Philippines, and was criticised by fans for being out of shape.

After a year’s delay due to the coronavirus pandemic, the Tokyo Olympics sports programme finally opened today with softball in disaster-hit Fukushima.