Las Vegas: Who uses the new ball better – Australia or England – will determine the winner of the 2009 Ashes series, believes former leg-spinner Shane Warne.

"They have to take early wickets because they are going to be flat wickets," the Courier Mail quoted Warne as saying in the gambling capital of the world.

He also said that this series would determine Ponting's captaincy?

"After the 2005 series loss in England, I think he will feel there is some unfinished business. He was the first Australian captain in decades to lose the Ashes in England. It is a big tour for him and his captaincy. His captaincy will be under the microscope from the media and former players, but I think he is up for it," said Warne.

He also said that spin could play a significant role in the series as the weather is hot in England at this time of the year and the wickets are going to be really dry.

As far as the bowling line up for Australia was concerned, Warne said that he expected Peter Siddle, Brett Lee and Mitchell Johnson to take the field at Cardiff on July 8.

"Mitchell Johnson has turned into a superstar. The other two pace spots are up for grabs. Siddle deserves his spot. He has earned the right to bowl in the first Test. The third spot … I would go with Brett, I think he deserves the opportunity to have the first crack at it," said Warne.

The batting line up was pretty much decided, he said, adding that Australia are definitely the favourites.

"I really believe that it will be a close series. England's recent form has been pretty ordinary, but they lift for the Ashes," he said.