Khan has rarely made news as a politician, and his hunger strike at the prison where he is being held for protesting against Pakistan's military ruler has put him back in the spotlight.
"Imran Khan's morale is high, and he says his protest will continue until the government reinstates the deposed chief justice," said Umar Cheema, a spokesman for Khan's Tehrik-e-Insaaf, or Justice Party.
President Gen. Pervez Musharraf purged the Supreme Court when he declared emergency rule more than two weeks ago, days before the tribunal was expected to decide on his eligibility to serve as president.
Khan's strike began Monday, shortly after a new Supreme Court stacked with judges hand-picked by Musharraf threw out most of the legal challenges to the Pakistani leader's re-election earlier this month.
Khan was jailed last week after being picked up at a banned rally in the eastern city of Lahore .
Prison officials deny he has stopped eating, saying his supporters are spreading word of the strike to attract media attention.
"Trust me, Imran Khan is not on a hunger strike. He ate yesterday, and he had his breakfast" - bread, eggs and fruit - "this morning in front of me," said Mohammed Bakhsh, the deputy superintendent of the jail in Pakistan 's eastern Punjab province where Khan is being held.
Khan has long been a vocal critic of Musharraf and the United States , the president's chief international backer. Authorities briefly put him under house arrest in 2006 to stop him from organizing protests when U.S. President George W. Bush visited.
But he has never managed to translate the immense popularity he earned as a cricket player - he led Pakistan to its only World Cup victory in 1992 - into political power. Khan is currently the only member of his party, founded more than a decade ago, to hold a seat in Pakistan 's 342-seat Parliament.
Yet he remains an influential personality and was among the first politicians targeted for arrest when the emergency was imposed Nov. 3. He managed to slip away and elude police until Thursday.