Klitschko first become involved in local Kiev politics in 2006, gaining a seat on the city council and twice unsuccessfully running for the post of mayor.
He founded the UDAR party in 2010 and the legislative elections represent its big chance to raise its status from a force in Kiev to a big national player.
He has also angrily rejected rumors that the party has links to the presidency, although it remains unclear if it will forge any anti-Yanukovych alliance with the Tymoshenko bloc after the polls.
For Shevchenko, defeat would be a rare setback in a glittering career, which in 2004 saw him win the coveted Ballon d’Or. However, critics are lining up to say he has made the worst mistake of his life by throwing his weight behind Korolevska.
Both sports stars may seek inspiration from Shevchenko’s former AC Milan partner Kakha Kaladze, who joined the opposition in his native Georgia. Kaladze is set to become energy minister in the new government after its election victory on Oct. 1.