Top British conductor Simon Rattle called it an "international treasure" and legendary maestro Zubin Mehta raved that he adored conducting it.

But when the man behind the Australian World Orchestra, Alexander Briger, first made known his plan to bring Australian musicians from all corners of the world together to form an orchestra, the task was deemed insane.

He still remembers striding into the Sydney Opera House in 2011 with his sister Gabrielle Thompson - who is now the orchestra's chief executive officer - armed with "a dream and a great deal of naive optimism".

"We walked in there and said, 'We want to book the concert hall. How much is it?' They told us, 'Well, it's expensive. What do you want to do?'" Briger, 47, says with a laugh.

"I said we wanted to fly all these Australians from orchestras from around the world in to form an orchestra and they went, 'You're going to do what? Are you crazy? How on earth are you going to do that?'

"We got that reaction a lot, people wondering if it could be done or the orchestra was just the ramblings of a madman."

Cobbling the orchestra together was a logistical feat that took grit and long hours hunting down funds and herding musicians - from renowned groups such as the Berlin Philharmonic - back Down Under for an intense schedule of rehearsals and shows.

Made up of rotating musicians, the orchestra has members from more than 40 orchestras worldwide under one roof. But Briger and Thompson proved it could be done.

In August 2011, the orchestra had its inaugural concert series in Australia with Briger - its chief conductor and the artistic director - at the helm. Audiences, he recalls, went "absolutely ballistic".

"There were standing ovations before we'd even played," says Briger, who has conducted top orchestras such as the London Philharmonic Orchestra. "The audiences were going, 'Wow, this is the level of talent we have coming from Australia. I had no idea we had this person in the Vienna Philharmonic or this person in the London Symphony Orchestra.'"

And this star-studded supergroup is headed to Singapore in October. It will play a one-night-only concert at the Esplanade Concert Hall on Oct 1, with 93 of Australia's finest classical musicians performing under Briger's baton.

It will take on two beloved pieces, Ravel's Bolero and Tchaikovsky's Symphony No. 5. And the concert will also see the international premiere of The Witching Hour, a specially commissioned concerto for eight double basses by Australian composer Elena Kats-Chernin.

Singapore violinist Brenda Koh, 21, a student at the Yong Siew Toh Conservatory of Music, will perform with the orchestra when it is in town (see other story).

The Singapore concert is only the second time the orchestra has performed outside of Australia. The only other time was in India last year.

"Australia has such great ties with Asia and, particularly now, Singapore. So the orchestra wanted to come here to play. It's very exciting and it's really a coming together of our two nations," says Briger.

After the success of the orchestra's first season in 2011, it decided to raise the stakes by courting one of the world's conducting greats.

"We wondered, could we get Zubin Mehta?" Briger says. "And there was this oboist Nick Deutsch, who plays in Zubin's Israel Philharmonic and is really good friends with him. Imagine the luck. So all he did was ring Zubin up and we managed to work things out."

Mumbai-born Mehta was at the helm of the orchestra's 2013 season, once more sparking a wave of standing ovations from audiences in Sydney and Melbourne.

And in Australia, he, too, had a chance to indulge in his other passion: cricket. Briger arranged for Mehta to meet top cricketers Steve Waugh and Brett Lee.

"Zubin just couldn't believe it. He was stunned," says Briger. "At the rehearsal after, he told the orchestra, 'I'm really speechless. I'm not sure how I'm going to conduct now. You're the only orchestra on earth that will understand this: I've just had afternoon tea with Steve Waugh and Brett Lee.' And the whole orchestra just burst into laughter."

Mehta was so impressed with the orchestra that he invited it to tour India with him. It headed there last year and, that same year, worked with another legend, Berlin Philharmonic principal conductor Rattle for its concerts in Australia.

This year, as the orchestra turns five, Briger will take charge once more.

As a young boy, he was already nimble with the violin and piano. But it was at age 12, after watching his uncle - the famous Australian conductor Charles Mackerras - lead the Sydney Symphony Orchestra that he decided on a career in music. "I still remember listening to one particular piece - Mahler's Fourth Symphony - and when the third movement came on, I was so blown away by this exquisite music that I said to myself right there and then, 'I want to do what my uncle's doing,'" he recalls.

Decades later, in 2006, he would come full circle, conducting that same piece with the London Philharmonic as his uncle sat in the audience.

"There's just something magical about music and how it can bring people together. That first year with the Australian World Orchestra, we saw all these players from all over the world - some who hadn't seen one another for 20 years or so - hugging and crying, tears streaming down their cheeks," he says.

"There's just something different about being part of this orchestra. Something more. For these musicians, it's not just a performance. It's a homecoming."

Singaporean in gig too

When some of Australia's leading classical musicians unite for a concert in Singapore, they will be joined by home-grown violinist Brenda Koh. Just 21, she was picked by the Yong Siew Toh Conservatory of Music - where she is a fourth-year student - to be part of the Australian World Orchestra Academy.

The opportunity gives young talents a one-time place in the orchestra - an honour given to just seven young people before Koh.

Before taking the stage with the orchestra for its performance here on Oct 1, she heads to Sydney late next month for rehearsals.

Koh, who took up the violin at age three, is looking forward to having a taste of life in a professional orchestra. "I can only imagine the level of commitment and passion these musicians have, and I can only hope I have the capacity to learn as much as I can from them ," she says.

She is doing a joint bachelor of music degree, spending five semesters at the Yong Siew Toh Conservatory of Music here and three at the Peabody Institute in the United States. An active chamber musician, she has taken part in chamber music festivals in Europe and the US and, in 2012, clinched the top prize for the inaugural Singapore Ensemble Competition.

The Australian World Orchestra is big on education and has been active in its efforts to share its members' knowledge and experience. Its musicians will also conduct masterclasses for Yong Siew Toh students on Oct 1, before its performance. Among them are Shannon Pittaway, who joined the New Zealand Symphony Orchestra last year as principal bass trombone after a decade with the Singapore Symphony Orchestra.

A Yong Siew Toh spokesman says the conservatory is pleased to partner the orchestra. "Australian World Orchestra's commitment to education through this partnership brings immense value to our students as well as the community."

Nur Asyiqin Mohamad Salleh