Matt Hopper, who was called into the squad on Monday starts at outside centre, partnering Leicester Tiger, Billy Twelvetrees.

Ugo Monye takes the number 11 shirt on the wing, while Joe Gray and George Robson start in the front five.

Gray's positional partner, Chris Brooker is the only Quin on the bench as Harlequins have the highest representation in the match day squad.

"It is a new era for us, there's a lot of youth and energy in this squad and we'll go into the game with a 'no fear' attitude," said Callard.

"We want to see the players express themselves and at the same time develop the streak of pragmatism you need to win big games. We've seen in Europe the strength of Irish rugby at the moment but the challenge motivates and excites us."

15 Delon Armitage (London Irish)
14 Ugo Monye (Harlequins)
13 Matt Hopper (Harlequins)
12 Billy Twelvetrees (Leicester Tigers)
11 Matt Banahan (Bath Rugby)
10 Freddie Burns (Gloucester Rugby)
9 Ben Spencer (Saracens)

1 Matt Mullan (Worcester Warriors)
2 Joe Gray (Harlequins)
3 Paul Doran-Jones (Northampton Saints)
4 Matt Garvey (London Irish)
5 George Robson (Harlequins)
6 James Gaskell (Sale Sharks, captain)
7 Andy Saull (Saracens)
8 Thomas Waldrom (Leicester Tigers)

Replacements: 16 Chris Brooker (Harlequins), 17 Rupert Harden (Gloucester), 18 Kearnan Myall (Sale Sharks), 19 Tom Johnson (Exeter Chiefs), 20 Paul Hodgson (London Irish), 21 Ryan Lamb (Northampton Saints), 22 Jonny May (Gloucester Rugby).