There are just four finalists left in the BBC singing contest all hoping to be crowned the 2014 winner.
Bookmaker Boylesports have given Tom Jones's representative Barker odds of 11/8 in the run-up to tomorrow's final, with Ricky Wilson's Christina Marie second favourite at 6/4.
Kylie Minogue's act Jamie Johnson follows at 5/1, with will.i.am's hopeful Jermain Jackman currently being placed as the outsider at 6/1.
Barker is thought to have been the odds-on favourite for a number of weeks, and her triumph would result in a second win for Team Tom (who was victorious in series one with Leanne Mitchell).
Barker is thought to be performing 'Both Sides, Now' by Joni Mitchell as her final solo song and her duet with Jones is rumoured to be 'Walking In Memphis' by Marc Cohn.
Other performances are said to include 'Wrecking Ball' by Miley Cyrus (Jermain Jackman), 'Fix You' by Coldplay (Christina Marie) and 'Missing You' by John Waite (Jamie Johnson).
The Voice final takes place tomorrow (April 5) at 7pm on BBC One