MELBOURNE - Australia have left out fit-again paceman James Pattinson for Sunday's opening one-day international with England at the Melbourne Cricket Ground. Skipper Michael Clarke admitted at his pre-match media conference on Saturday he had no answers on why Pattinson was not selected. Pattinson's absence comes as Australia rest their Ashes player of the series and leading wicket-taker Mitchell Johnson from game one of the five-match ODI series.Opening batsman Shaun Marsh has also been unable to win selection for Sunday's opener, with Aaron Finch likely to partner David Warner at the top of the order and Shane Watson at number three. Pattinson was sent home from the 2013 Ashes tour with a back injury, but he has claimed seven wickets in three Big Bash League games recently. While Australia's ODI series with England is a crucial warm-up for the 2015 World Cup to be hosted by Australia and New Zealand, it's also a chance for players like Pattinson to audition for a spot in the Test squad to tour South Africa in late January."That's probably a question for the selectors," Clarke told reporters. "I don't know what they said to James and I don't know why they decided to not pick him. But I think James certainly is realistic and understands that he's only been back bowling for a couple of weeks in regards to game practice. He's looking fit and I'm sure he'll play a big part throughout this series."Clarke said Australia would take winning momentum into the ODI series, but that would come from Australia's 2-1 ODI series win in England in September rather than their recent five-nil Ashes whitewash. Australia are rated second in ODI cricket behind India, with England at three. "We as a team have no complacency, where you're sitting there expecting that because the result was five-nil in the Test series, that the one-day result will be the same," Clarke said.Australia's pace attack consists of Clint McKay, allrounder Shane Watson and inexperienced pair James Faulkner and Nathan Coulter-Nile. "I have a lot of faith and confidence in Clint," Clarke said. "Clint has been a very good performer over a long period of time for us and Twenty 20 cricket is different to one-day cricket." England have rested star batsman Kevin Pietersen for the ODI series, while paceman Stuart Broad will miss the first two games after carrying England's pace attack in the Ashes. "We came here to take the Ashes home," England skipper Alastair Cook said. "Now that we've lost them, if we win this one-day series we salvage some pride from our performances." SQUAD: Michael Clarke (capt), George Bailey, Nathan Coulter-Nile, Xavier Doherty, James Faulkner, Aaron Finch, Brad Haddin, Clint McKay, Glenn Maxwell, David Warner, Shane Watson.