Having blazed a trail for Singapore swimming, Olympic 100m butterfly champion Joseph Schooling believes team-mate Quah Zheng Wen can join him as an Olympic medallist sooner rather than later.

At the ongoing Rio de Janeiro Games, Quah reached the 100m and 200m fly semi-finals. The 19-year-old also clocked personal bests in both events.

Yesterday, Schooling, 21, said: "He's improving. Two semi-finals, that's phenomenal. He has a lot more potential.

"I think he can definitely win a medal or even win (a race) in 2020, if he keeps on this path."

Reflecting on their time at the London Olympics as rookies four years ago, Schooling said: "We were both struggling in London. We were both starstruck, (with) all the (big names) around us.

"But now we're among the best in the world. It's nice seeing him grow next to me. He pushes me, I push him, we want to be better swimmers."

Last year, Quah was granted national service deferment until the end of this month. It is unclear if the 19-year-old will have it extended until the 2020 Games.

Racing in the US and especially in the National Collegiate Athletic Association swimming meet, known to be one of the most competitive races in the world, has helped turn Schooling into a bona fide contender on the world stage.

The University of Texas at Austin student stopped short of encouraging Quah to join him in the United States, where he has been based since 2009.

But the swimmer believes the existing infrastructure in Singapore is strong enough to nurture an Olympic medallist.

Schooling's decision to train abroad was in part due to the closure of the Centre of Excellence, where the nation's best swimmers trained together.

But a similar system has since been revived with the formation of a National Training Centre squad that trains under national coach Sergio Lopez and his assistant Gary Tan.

"There's no Schooling way of (success). Everyone's different. But I do think we now have the resources, exposure, and belief now - that's the most important," said Schooling.

"Zheng's good enough to succeed anywhere he goes. I'd (only) advise him to do what he thinks is right."

With Quah and him leading the way, Schooling is optimistic about Singapore's chances of fielding a relay team at the next Games, especially the 4x100m medley relay.

The national record is 3min 38.25sec, while the lowest qualifier in Rio was Greece in 3:34.41.

Schooling said: "We should've swum the relay at (this) Olympics. That's my fault, I botched the fly leg during the medley. I just got caught up with winning the bronze, the pressure's off. I should (have approached) the race differently.

"We're so close. Zheng's getting better, I'm improving, there are young guns coming up. We have a great shot at making it."