Mikhail Prokhorov, Russian billionaire tycoon and owner of the New Jersey Nets basketball team, said Monday he will run against Vladimir Putin in next year’s presidential election, according to reports.

Prokhorov, whose wealth is estimated at $18 billion by Forbes magazine and has been careful not to cross Putin, the current Russian Prime Minister, was ousted in September from the pro-business Just Cause party.

Recent allegations of widespread voting fraud during Russia’s Dec. 4 parliamentary election triggered massive anti-Putin protests across the nation over the weekend.

Prokhorov’s candidacy may now pose a serious challenge to Putin.

Prokhorov said he had not discussed his decision with anyone in the Presidential administration, according to state-run news agency RIA Novosti.