Australia captain Michael Clarke has announced the World Cup Final will be his last one-day international match, opting to retire from the 50-over game after his third World Cup to prolong his Test career.

Clarke made the shock announcement at his official captain's press conference before tomorrow's showpiece event at the MCG.

He said he only told teammates just 10 minutes before telling the world's media assembled at MCG. Clarke opened his press conference by saying: "Just so everyone is aware, tomorrow will be my last ODI game for Australia.

"I've just spoken to my teammates and spoken to (Cricket Australia CEO) James Sutherland and (National Selection Panel chairman) Rod Marsh and (Bupa Support Team head coach) Darren Lehmann and informed them tomorrow will be my last ODI for Australia.

"It's certanly been an honour and a privilege to represent my country," Clarke added. The World Cup final will be his 245th ODI for Australia since his debut in 2003.

Part of the all-conquering 2007 World Cup team, Clarke took over the captaincy following the 2011 World Cup which eneded at the at the quarter-final stage with defeat to India.

"I think it's the right time for me and the Australian cricket team," Clarke said. "I was very fortunate four years ago to get the opportunity for me to captain this one-day team.

"That was very good preparation for me leading up to this World Cup and I think the next Australian captain deserves the same opportunity.

"I don't think it's reasonable to expect I'll be fit and healthy and available for the next World Cup, so I believe it's the right time."

George Bailey has stood in as captain during Clarke's injury-enforced ODI absences over the past 12 months, however Steve Smith is widely expected to be confirmed as Clarke's successor.

After standing in for Clarke during the summer Commonwealth Bank Test series against India, the 25-year-old Smith made his 50-over captaincy debut against England in Hobart during the Carlton Mid ODI series in January and is seen as a longer-term captaincy option for Test and ODI formats.

"Smithy has certainly matured as a player and a person," Clarke said.

"I don't think it would be fair for me to go into who is going to be the next captain, it's not my place. It's up to the selectors."

Clarke said a large motivator for him to walk away from ODIs was to try and prolong his Test career.

"That's obvioulsy a priority for me to continue to be successful in the Test format. By walking away from one-day cricket it probably gives me my best opportunity.

"I don't feel bad about saying I feel that Test cricket is the toughest part of our game.

"I love that challenge. I see it as the pinnacle ... I feel like I've still got a lot to offer the Australian Test team as captain."

Clarke battled back from hamstring surgery to take his place in Australia's 15-man World Cup squad and, after missing the tournament opener against England, replaced stand-in skipper Bailey in the XI for Australia's remaining games.

Clarke said he made the decision to retire after Australia's semi-final win against India at the SCG on Thursday.

"I think I got back to my house at about 12.30am. Kyly was in bed and that's when I spoke to her about it," he said.

"I know I've made the right decision.

"I told my teammates 10 minutes ago. I told the selectors and James Sutherland about an hour ago."

Sutherland said Clarke's decision had caught him by surprise but the batsman would leave as one of Australia's "greats".

"From the time that he burst onto the scene as an exciting 21-year old way back in January 2003, he was always destined for great things," said Sutherland.

"While his decision comes as something of a surprise, Michael leaves one-day cricket on his own terms, aiming to finish on an absolute high, in front of a packed MCG as a possible World Cup-winning captain. That’s very special.

"Regardless of the result, he will leave the one-day international game as one our greats. We thank him for his wonderful contribution to one-day cricket and look forward to his continued leadership at Test level."

Clarke has demoted himself down the order on more than one occassion in this World Cup and said he would not hesitate to do the same in Sunday's final.

"If it's best for the team for me to bat at No.4 I'll bat at No.4. If it's best for the team for me not to bat I won't," Clarke said.

Clarke's retirement is the latest of many stars of the game to retire from 50-over cricket at this tournament. Sri Lanka stalwards Kumar Sangakkara and Mahela Jayawardene have both played their final ODI, as have enigmatic Pakistan pair Shahid Afridi and Misbah-ul-Haq. Zimbabwe skipper Brendan Taylor also stood down from cricket after his county's exit, and it is also expected to be Daniel Vettori's final game for the Black Caps after the spinner was coaxed out of retirment for the tournament.

Clarke, who turns 34 on Thursday, made his debut as a blond 21-year-old dasher in 2003 against England, scoring 39 not out in a four-wicket win at the Adelaide Oval.

Following Australia’s quarter-final exit in the 2011 World Cup at the hands of India, Clarke was handed Australia's ODI reins after Ricky Pointing stepped down.

Clarke has captained his country 73 times in the 50-over format, and will record his 50th win at the helm should Australia prevail tomorrow and capture their fifth World Cup title.

Clarke's stellar ODI career

Started in 2003 when he made 39 not out against England at Adelaide Oval

Left out of the squad for the 2003 World Cup in South Africa, which Australia won without dropping a game

Dominated the 2007 World Cup in the West Indies, scoring 436 runs at an average of 87.2

Appointed vice-captain in 2008 after the retirement of Adam Gilchrist

Led the side for the first time in 2008 when Ricky Ponting was injured, Australia winning by one run but Clarke copping a fine for the side's slow over rate

Scored eight in the 2011 World Cup quarter-final, when Australia's hopes of a fourth straight crown were dashed by eventual champions India

Ponting stepped down from the leadership post a week after the 2011 tournament, with Clarke becoming both Test and ODI captain

Back and hamstring issues in 2013 and 2014 meant he played 11 of a possible 33 ODIs leading up to the 2015 World Cup

Was passed fit for Australia's second pool game in the 2015 World Cup, the deadline selectors had nominated for him to take part in the tournament after hamstring surgery

Told teammates, selectors and Cricket Australia on Saturday that the 2015 World Cup final would be his last ODI

ODI runs: 7907 at average of 44.42 (only Australians to have scored more are Ricky Ponting, Adam Gilchrist and Mark Waugh)

World Cup runs: 814 at average of 62.61 (only Australians to have scored more are Ponting, Gilchrist, Waugh, Matthew Hayden, Steve Waugh and David Boon)

High score: 130 in a ODI against India at Bangalore in 2007 that was washed out

Record as captain: 49 wins from 73 ODIs

ODI runs as captain: 2671 at average of 45.27