Joseph Schooling has gone from poring over videos of Michael Phelps' races to competing alongside him - to now beating the American in his best stroke.

But even as a victory over the greatest Olympian in history, five years after they first faced off, provided confidence and contentment, the Singaporean refused to let it lead to conceit.

His 51.58-second effort in the 100m butterfly at the Longhorns Elite Invite on Friday saw him out-touch Phelps, who followed with 51.65sec. Another American, Jack Conger, was third in 51.72sec.

Schooling's time is the seventh-fastest in the world this year.

"I'm a little happy, but not overjoyed," Schooling, who turns 21 next week, told The Sunday Times from Austin, Texas.

The familiarity of racing in his "home pool" - the meet was held at the University of Texas where he is a sophomore - also helped.

He added: "It's always nice going one up during an Olympic year, (but the) most important thing is this summer."

This summer - the Rio de Janeiro Olympics in August specifically - is when Schooling wants a repeat, at least, of the kind of form that took him to a personal best of 50.96sec and a historic bronze medal at last year's World Championships.

This summer will be when a more polished finish - better than the one he described as "pretty pathetic" on Friday - is crucial.

But until then, a first win over his childhood idol in their first race together this year is a clear morale booster for Schooling.

"Michael is still doing hard training and just came out from altitude (training). Right now, it feels great. I've got to be even better in two months," he told Swimming World Magazine shortly after his win.

Indeed, national assistant coach Gary Tan said it is hard to say if Phelps, who had won the 100m freestyle five races earlier, had tapered for the competition.

But the fact that the 18-time Olympic champion is using the Austin meet as a final tune-up before the crucial US Olympic trials in Nebraska at the end of the month means his mind and body are both ready to race fast.

The result should be gauged against how good a racer Phelps - who at 30 is still the fastest American butterfly swimmer - still is, added Tan. The American holds the 2009 world record of 49.82sec, clocked in the era of the supersuits that are now banned.

Said Tan, noting that the American had become a first-time father just a month ago: "Phelps is now a guy who has never been more stable or happier in his life.

"Whether or not this result translates to the Olympics is a different question altogether, but this is a very, very good position for Joseph to be in right now.

"To be just 0.5sec off your personal best even when you are not fully tapered and rested is very good."

Besides Phelps, Tan named South African Chad le Clos and Hungarian Laszlo Cseh as the rivals whom Schooling should also benchmark himself against. Cseh is the only one to have gone below 51sec this year with a 50.86sec effort at the European Championships last month.

Schooling is due to join the rest of his national team-mates for a training camp in Florida later this month. The squad are currently competing in the Indianapolis Arena Pro Swim, where Quah Zheng Wen posted several creditable swims.

He was fastest in the preliminaries in the 200m freestyle, 100m fly and last night's 200m fly (1:58.09).

The 19-year-old posted a personal best of 1:49.48 in the 200m free, but opted out of the final to concentrate on the 100m fly where he clocked 52.45sec to finish second behind Canadian Santo Condorelli (51.98sec).

Said national coach Sergio Lopez, who is in Indianapolis with his charges: "Zheng Wen lost a little bit of pace in the last 35m with his stroke. Regardless, he's swimming well and I'm very happy with his swims and the way he is approaching the competition."

Quah is swimming the 200m fly final this morning, while Schooling is also pencilled in for the same event in Austin today.