Updated

By Gennady Fyodorov

MOSCOW (Reuters) - After making a fortune trading Siberia's metal riches, Russia's tallest tycoon is now focused on trying to transform a lowly National Basketball Association team into champions.

Towering over his colleagues at 6-foot-7 (2.01m), Mikhail Prokhorov brings a fortune estimated at $18 billion to his new role as owner of the NBA's New Jersey Nets.

The 45-year-old Russian, who is the league's first majority investor from outside North America, also brings a passion for sport and lofty expectations for a championship team.

"If everything goes as planned, I expect us to be in the playoffs next season and win a championship in one year minimum, and maximum in five years," Prokhorov said during a briefing in New York a week after his bid to purchase the Nets won approval from the league.

But in typical flippant style, the Muscovite declined to say how he would turn a team that set a record for the worst start to an NBA campaign last year into champions overnight.

"If I tell you, I would have to kill you," said Prokhorov.

Russian media have already built up Prokhorov's latest acquisition and compared it to Roman Abramovich's purchase of London soccer club Chelsea in 2003.

"Undoubtedly, it should have a similar impact on American sports as Abramovich had on Britain and the rest of Europe with his purchase of Chelsea," Vladimir Geskin, editor of leading Russian sports daily Sport-Express, told Reuters.

"I think in the long run it would greatly enhance the image of Russian sports and business in the U.S."

SPORTS AND WOMEN

Helped by his height, Prokhorov was a keen basketballer in his youth but his real sports passion now lies with skiing and kickboxing.

Until recently, he owned a number of Russian professional teams, including European basketball powerhouse CSKA Moscow, but sold most of his sports assets a year ago. In 2008, he was elected president of the Russian Biathlon Union.

He built a fortune by acquiring some of the juiciest assets of a former superpower on the cheap during chaotic years after the fall of the Soviet Union and selling them at top prices just months before the global financial crisis.

His masterstroke was helping to buy Norilsk Nickel, the world's biggest nickel and palladium producer, from the state in the privatizations of the 1990s.

Prokhorov sold his share in Norilsk and other assets for billions just months before the global crisis hammered the value of Russian assets. He refuses to speak about his wealth.

"It's very rude to ask a girl her age. It's much worse to ask how much cash you have," he told Reuters in 2008.

Ranked by Moscow's Finans magazine as Russia's second richest man, after steel tycoon Vladimir Lisin, Prokhorov has a fortune of $17.85 billion.

(Additional reporting by Guy Faulconbridge)