Mayne spent most of the 2006 season recovering from a groin injury and only played four games. He recovered in 2007, but was now too old to represent WA at the National Under 18s Championships that most potential AFL draft picks attend.
In 2007 he made his debut for Perth in the WAFL and was amongst their best players in his second match. Noticeable on the field with his curly blonde hair, the strong marking forward played eight games for Perth in 2007.
In 2008 he made an impressive debut for Fremantle in an exhibition match in South Africa against Carlton, kicking two goals. He wears jumper number 23 for Fremantle, being only the second player to ever wear that number after the retirement of Fremantle games record holder Shane Parker at the end of the 2007 season.