A baggy green cap worn by late Sir Don Bradman during the 1948 'invincibles' Ashes Tour is all set to fetch a record-breaking 600,000 Australian dollars when it goes under the hammer at an auction here on December 15.

The cap was bought by one Tim Serisier after he won $250,000 in reality show ‘Who Wants To Be A Millionaire’. Serisier now wants to auction the cap and though auctioneer Charles Leski says a better timing could have fetched a higher price, the piece of record can still invite a bulky bid in the range of $600,000 to 750,000.

Speaking with 'The Sydney Morning Herald', Leski said, “I defy anybody to tell me anything in Australian sport that is more important or has a higher status.”

"This is the single most valuable item we've ever auctioned - sporting, Australian, across the board," he added.

Bradman gave this cap to his English godson Richard Robins for his 12th birthday in 1954. Richard Robins' father, Walter, played 19 Tests for England and was Bradman's "best pal in the cricket world." Since 1954, the cap had been in England.

Recently, a Bradman bat was sold for a world record $145,000.