Pontypridd need to overcome a 15-point deficit against the Zurich Premiership's in-form team if they are to advance to the Parker Pen Cup final.
PARKER PEN CUP SEMI-FINAL, SECOND LEG
Pontypridd (19) v Wasps (34)
Where: Sardis Road
When: Friday, 25 April
KO: 1905 BST
The London side have won their last nine successive games and coach Warren Gatland says Pontypridd will have to play "exceptionally" to stand a chance.
"It'll be tough to play Pontypridd away but if anyone's going to beat us by 15 points at the moment they're going to have to play very well," said Gatland.
"Sardis Road is an intimidating place to go and get a win, but we're going down there to play our normal game."
Pontypridd coach Lynn Howells feels that a final spot is within his side's grasp, and they are sure of fervent support for a game that could be the valleys side's last in a turbulent history of European rugby.
"It's obviously a difficult task, but we're at Sardis Road and we never give in there," he said, "We owe the supporters a performance - they were great up at Wasps."
"We were certainly second-best in the first half of the first leg, but I didn't think we were 15 points worse than them overall.
"I thought we were naive in the contact area. We have to stop them on the gain-line - they won't like that."
Wasps make five changes to the side that beat Bristol last Sunday, Josh Lewsey moving from wing to full-back in place of Mark Van Gisbergen.
Mark Denney replaces Stuart Abbott at centre, with Kenny Logan and John Rudd on the wings.
Former Wales scrum-half Rob Howley injured his ankle in the Bristol game, but he is fit to play.
Howells says Ponty were beaten at the contact area in the first leg
The only change in the forwards sees Phil Greening replace Trevor Leota at hooker.
Pontypridd's major concern is at number eight. Michael Owen damaged knee ligaments in Saturday's league defeat at Swansea and will be out for six-to-eight weeks, while Nick Kelly and Geraint Lewis are out with thumb and shoulder problems respectively.
Veteran Dale McIntosh is named in the back row, with Kingsley Jones on the bench.
Scrum-half Paul John will not recover from his knee ligament injury in time to play and Jonathan Hooper is also out, leaving either centre Jason Lewis or on-permit veteran Kevin Ellis to cover from the bench.
Pontypridd: Brett Davey; Gareth Wyatt, Sonny Parker, Jon Bryant, Matthew Nutthall; Ceri Sweeney, Gareth Baber; Gethin Jenkins, Mefin Davies (capt), Duncan Bell, Brent Cockbain, Robert Sidoli, Richard Parks, Wayne O'Connor, Dale McIntosh.
Replacements: Shaun James, Neil Jenkins, Matthew Rees, Neil Hennessy, Mark Lewis, Kingsley Jones, Kevin Ellis / Jason Lewis.
Wasps: Josh Lewsey; John Rudd, Ayoola Erinle, Mark Denney, Kenny Logan; Alex King, Rob Howley; Craig Dowd, Phil Greening, Will Green, Simon Shaw, Richard Birkett, Joe Worsley, Paul Volley, Lawrence Dallaglio (capt).
Replacements: Stuart Abbott, Mark Van Gisbergen, Martyn Wood, Mark Lock, Peter Scrivener, Alistair McKenzie, Trevor Leota.
Ref: Joel Dume (France)