Ukraine's best-known sports stars, boxing champion Vitali Klitschko and the footballer Andriy Shevchenko, are both vying for power in Sunday's parliamentary elections in a bid to send a shockwave through Ukrainian politics.

Heavyweight Klitschko, 41, who fought his last bout in September, leads his aptly named UDAR (punch) party which analysts see as an increasingly serious challenger to the ruling party of President Viktor Yanukovych.

Meanwhile Shevchenko, 36, stunned both his fans and commentators when he dramatically hung up his boots after the Euro football championships this summer to become a key figure in the pro-business Ukraine Forward! party.

Their entry into the election campaign shook up Ukrainian politics, which for the past years has turned into a two-way duel between the factions of Yanukovych and his now jailed rival Yulia Tymoshenko.

According to opinion polls, UDAR could emerge as the main challenger to Yanukovych's Regions Party in the elections, pushing the Tymoshenko-led coalition into third place with more than 15 percent of the vote.

"The voters are disappointed with the authorities, the opposition and politicians. People need to believe in something and Klitschko has now become the hope," said Volodymyr Fesenko, director of the Penta centre for political studies.

By contrast, the prospects for Ukraine Forward!, led by former Tymoshenko ally Natalya Korolevska, appear less rosy: polls suggest it will receive a small percentage of the vote and fail to cross the five-percent threshold into parliament.

Even these fresh faces in the rough-and-tumble world of Ukrainian politics have had to endure a degree of cynicism about their motives. Shevchenko was forced to deny allegations he was being paid for his work.

Campaign posters plastered across Kiev for Ukraine Forward! show Shevchenko standing somewhat intimately next to Korolevska, an image that has been the subject of much mockery among Ukrainians.

"Shevchenko's move into politics has not had the expected effect and I think he many still be thinking about his future in politics," Fesenko told AFP.

Klitschko's party, whose full name is the Ukrainian Democratic Alliance for Reform (UDAR), accuses its foe Regions Party of rampant corruption and promises a European future for Ukraine.

"We want to live in a normal, democratic country, where the rule of law works," the boxer declared during the campaign.

Ukraine Forward! has been accused of lacking any coherent programme and even being merely a front set up by the Regions Party to soak up potential votes for the opposition -- allegations vehemently denied by its leaders.

But Shevchenko is clearly trying to tap on a sentiment that Ukraine's political leadership has lost contact with the people.

"I have finished my sporting career and I have returned to Ukraine to live and work there," said the former AC Milan superstar, who also played for Chelsea as well as his native Dynamo Kiev.

"I want to live in a prosperous country and not in one that belongs to a few oligarchs and an elite of officials who adopt laws for themselves," he said.

Shevchenko's entry into politics was as sudden as it was surprising, but Klitschko, whose brother Vladimir is also a heavyweight boxing champion, has been building up his political base for several years.

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 rumours 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, during which in 2004 saw him win the coveted Ballon d'Or. But 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 October 1.

[Image via Agence France-Presse]