"I find my work as much fun as any other sport, it is more like a stress buster," says the 37 year-old tennis, cricket and squash enthusiast.

"Every two years I get into a new sport, complete with a new coach, and keep at it till I get to fairly close to the professional level," says Oberoi. His other passions are extreme sports like bungee jumping - "I just love the adrenaline surge!" he says.

And he brings the same enthusiasm to work. Oberoi, who believes in working only eight hours a day ("but eight hours with complete concentration, mind you!"), has single-handedly turned around the small construction firm started by his father. Oberoi Constructions is today valued at $1.4 billion.

The turning point for Oberoi Construction was the 2002 acquisition of the 60-acre Novartis property in Goregaon for Rs 100 crore (Rs 1 billion). It is this property that is today being developed into the group's flagship township in the western suburb of Goregaon with luxury residences, malls and a hotel.

Oberoi's credibility in the market also went up a notch more when he partnered with ICICI Ventures to buy the Glaxosmithkline property in Mumbai's prime Dr Annie Besant Road (Worli) in 2004.

Says Arun Puri of Trammell Crow Meghraj, "With the ICICI Ventures partnership his credibility in the market suddenly went up. Though others like Rahejas were also in the fray for that property, Oberoi's tie-up with ICICI put him leagues ahead of others. He was no longer just a builder."

Oberoi, who did an owners and presidents management (OPM) course from Harvard in 1997 (Bharti's Sunil Mittal did the same course in 1994), made waves most recently when he sold two flats in super deluxe Oberoi Skyz in central Mumbai's Worli to retail tycoon Kishore Biyani of the Future's group for a whopping Rs 20 crore (Rs 200 million) each.

But the company which is best known for its quality residences in Mumbai's western suburbs stepped into international limelight only when Morgan Stanley picked up a 10 per cent stake for Rs 675 crore (Rs 6.75 billion) in January this year.

The company, which has had a primarily Mumbai footprint, is currently exploring other locations such as Pune, Bangalore and Hyderabad.

"Having made it in the most difficult market in the country, Mumbai, we can repeat our success anywhere in India," says a confident Oberoi. The company has also entered into a tie-up with Dharmesh Jain of Nirmal Lifestyles and Vinod Goenka of Conwood for a hospitality foray.

Making it to the billionaires club has been a humbling experience for Oberoi. "People look up to you more and I can sometimes feel the weight of it on my shoulders," says this builder who prefers a low profile despite keeping high profile company like close friend film star Akshay Kumar and actress wife Gayatri Joshi.