"It would be a major achievement to beat Australia and come back from this tournament ranked third in the world," said Burnell.
"However, it certainly wouldn't be undeserved as everyone in the squad, from the players and management to the backroom staff, has put in so much time and effort in order to leave no stone unturned. Everyone has worked flat out throughout the three week period and to win tomorrow would be massive.
"Australia are last year's champions and a very good side so it won't be easy for us but if we can get our game right and rectify certain errors, I am confident we are capable of a result. We had a 15 minute lapse at the start of both our games against New Zealand which cost us dearly so we must start well in this play-off in order to steal a march on our opponents.
"We showed great attitude and enthusiasm in our second half, semi-final performance which was very encouraging despite letting a try slip in at the end. We have a very positive bunch of boys in this team.
"They are a tight group and the players have really come into their own during the Championships. I'm sure that they have done themselves no harm whatsoever in staking their claim for regular spots in Premiership sides next season and beyond."
Burnell has made six changes to his starting line-up for this third place play-off. Centre Tom Williams and prop Sam Hobbs gain their first starts of the campaign, while Rhys Webb returns at scrum half for Gareth Williams, who has returned home after being concussed against New Zealand.
Ben Roberts starts instead of Huw Dowden at hooker, Nathan White replaces Haydn Pugh at lock and Lloyd Phillips comes in for Jevon Groves in the back row.
IRB U19 World Championships
Third place play-off: Wales v Australia (Saturday April 21st, 5.30pm, Ravenhill, Belfast)
Please note: the match will be televised on BBC NI (Sky Channel 992) or on BBC2 via the red button.
Daniel Evans (Llanelli / Scarlets)
Jimmy Norris (Bedwas / Dragons)
Tom Williams (Bridgend / Ospreys)
Rhys Williams (UWIC/ Scarlets)
Leigh Halfpenny (Neath / Ospreys)
Gareth Owen (Maesteg / Ospreys)
Rhys Webb (Bridgend / Ospreys)
Ryan Bevington (Bridgend / Ospreys)
Ben Roberts (Ebbw Vale / Dragons)
Sam Hobbs (Pontypridd /Blues)
Nathan White (Bridgend / Ospreys)
Josh Turnbull (Llanelli / Scarlets)
Lloyd Phillips (Narberth / Scarlets)
Nicholas Cudd (Tumble / Scarlets)
Sam Warburton (Capt, Wanderers / Blues)
Huw Dowden (Beddau / Blues)
Lloyd Elliott (Ospreys)
Phillip Price (Bridgend Athletic / Ospreys)
Haydn Pugh (Llangennech / Scarlets)
Jevon Groves (Cardiff /Blues)
Jonathan Griffiths (Glynneath / Ospreys)
Tom Edwards (Ebbw Vale/ Dragons)
Jason Tovey (Newport / Dragons)
Gruff Jones (Llandovery /Scarlets)
Nicholas Harwood (Bonymaen / Ospreys)
James Egan (Cardiff / Blues)