Profile: Mikhail Prokhorov, Russian billionaire
Russian tycoon Mikhail Prokhorov, who has said he will stand against Vladimir Putin in next year's presidential elections, is one of his country's richest men and owner of the New Jersey Nets basketball team.
Mr Prokhorov is the billionaire founder of the Onexim Group, which has a wide variety of interests, with gold and nickel mining at their core, and is ranked by Forbes as Russia's third richest man with a fortune of around $18bn (£11bn; 13bn euros).
He had stayed out of politics until a few months before December's parliamentary elections, but then became leader of the Kremlin-backed liberal Right Cause party. Within weeks he had resigned, alleging Kremlin interference.
It is his earlier closeness to the Kremlin that has prompted some Russian political figures to suggest he has come forward to challenge for the presidency merely to provide liberal voters with a candidate and to draw attention from recent anti-Putin protests.
Mr Prokhorovtold the New York Timesthat nobody was interested in him until he bought the New Jersey Nets. He underwent media training to make him a more palatable owner to American basketball fans - reportedly watching Katie Couric's interview with Sarah Palin for tips on what not to do on camera.
"America, I come in peace," he said to US journalists at a press conference in New York to introduce him as the new owner of the basketball team.
Mikhail Prokhorov was born in Moscow in 1965. His father worked for the Soviet State Sports Committee and his mother was a research scientist.
After studying at the Moscow Finance Institute (now the Finance University) he went to work in the banking sector.
As chairman of Onexim Bank he was able to buy a stake in Norilsk Nickel during the largely unregulated sell-off of Russian industries in the 1990s.
He founded Onexim Group, a private investment holding company, in 2007. As well as metals the group has businesses in the financial industry, media and technology.
As head of the labour market committee of the Russian Union of Industrialists and Entrepreneurs (RSPP), he has campaigned for reform of the labour code.
Among his most controversial ideas is the introduction of a voluntary 60-hour working week.
In 2010 Mr Prokhorov bought a controlling interest in the New Jersey Nets - the first owner of a National Basketball Association (NBA) team to be from outside North America.
On his website he says that his parents instilled in him a great love of sports and as well as basketball he enjoys kick-boxing, track athletics and skiing: he serves as chairman of Russia's Union of Biathlonists.
Mr Prokhorov told CBS News that he was nicknamed "giraffe" at school because of his height - he is more than 2m tall.
The New York Times reports that his father was responsible for sourcing extra long beds for basketball players competing at the 1980 Moscow Olympics and ordered an extra one for his son.
In January 2007 he was arrested on suspicion of arranging prostitutes for guests at a party he hosted in the French Alpine resort of Courchevel.
The case was later dismissed, and Mr Prokhorov was cleared.
The arrest was not all bad news however, as it meant he had to sell his stake in Norilsk Nickel - a stake which subsequently dropped massively in value.
"It's a part of any business, to be lucky,"Mr Prokhorov told CBS. "Miracle happens!" he added.
In 2008, he launched a Russian online and glossy lifestyle-and-business magazine entitled Snob and later took the project to the UK and the US.
In an October 2010 interview at the time of the US launch he said the "energy and drive" of New York reminded him of Moscow, adding that he had no plans to live anywhere but Moscow.
By June 2011 he had entered Russian politics, becoming leader of the pro-Kremlin Right Cause party. He invited one of Russia's best known singers, Alla Pugacheva, to join his group, with the aim of fighting December's parliamentary elections.
But the party's September congress descended into chaos and Mr Prokhorov quit.
He launched a stinging attack on Kremlin strategist Vladislav Surkov accusing him of behaving like a "puppet-master" and organising a mutiny within the party's ranks.
His rise in politics had already been widely perceived as a Kremlin attempt to have a loyal party secure the liberal vote. His decision to stand in the 2012 presidential elections has been treated with similar scepticism.
Communist leader Gennady Zyuganov and opposition leader Boris Nemtsov both saw the move as inspired by the Kremlin.
Mr Nemtsov said the plan was an attempt to distract the attention of liberal protesters and stop "the wave of popular dissent". The billionaire magnate's goal is, in his eyes, an attempt "to preserve Putin's regime".
Mr Prokhorov has appeared to identify with the protesters, announcing to reporters that Russian society was "waking up".
It may not have helped his cause that he did not join the Moscow demonstration two days before.