In one motion he steered the puck into the open side before Vokoun could recover.
Stafford has been so snake bitten that he fanned on a one-time attempt while facing a wide-open side in the loss to Ottawa on Tuesday.
Haskell, normally a blind-side flanker, replaces Moody on the open-side, while Wood comes in for Tom Croft and Deacon replaces Courtney Lawes.
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Williams starts at open-side, with Colin Charvis switching to blind-side and Michael Owen coming onto the bench.
Leinster's in-form Sean O'Brien is selected at number eight with open-side David Wallace completing the back row.
The Dragons, who are also looking to recruit an open-side flanker, have parted company with Lee Hinton.
Callahan cut across the front of the crease and scored into the open right side of the net.
Robin Sowden-Taylor is seen as Williams' eventual replacement on the open-side flank and is included in the squad.
Tom Rees is set to start at open-side ahead of Michael Lipman, while the number eight position is uncertain.
Open-side Mark Rennie went close also, but the Ospreys' scramble defence held out.
Moody's injury could open the way for specialist open-side flanker Steffon Armitage to step up from the Saxons squad.
Delve will start at number eight, captain Ryan Jones switching to six with Jonathan Thomas moving across to the open-side.
Open-side flanker David Wallace is replaced by O'Brien while Leamy gets the number six jersey ahead of Ulster's Stephen Ferris.
Quins went on the offensive, and when Sharks open-side Lobbe was show a yellow card Sale looked ready to crack.
Wasps' Joe Worsley replaces Lewis Moody at open-side flanker, while Leicester lock Louis Deacon comes in for the injured Simon Shaw.
BBC: Worsley replaces Moody in England side to play Scotland
Fourie is expected to become England's first choice open-side flanker for the competition, after captain Lewis Moody suffered knee ligament damage.
Veteran Newport Gwent Dragons flanker Colin Charvis is hotly tipped to start at open-side given his continuing great vein of form.
The fixture will also double as a testimonial match for veteran open-side flanker Martyn Williams and raise money for selected charities.
With Moody expected to miss the first three Six Nations matches, Fourie is the only recognised open-side flanker in Martin Johnson's squad.
Sowden-Taylor had only been on the field at the Liberty Stadium a matter of minutes, replacing Wales and Lions open-side Martyn Williams.
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But the open-side panicked as Stuart Moffat closed him down, hurling a pass over his shoulder that Williams had little chance of fielding.
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Abrasive Scottish open-side Finlay Calder was chosen to lead the side, England's Roger Uttley named as forwards coach and Scotland's Ian McGeechan given overall control.
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Fulgence Ouedraogo, who had started both Six Nations matches so far, drops to the bench as a result, with Thierry Dusautoir starting at open-side flanker.
Scarlets open-side Dafydd Jones scored the pick of the game's tries, showing a deft side-step, while Gavin Evans also crossed for the struggling home side.
But the open-side returned in the Welsh derby, easing into the first half before exploding after the break, setting up the match-sealing try for Gareth Cooper.
While the backs will take the plaudits, both tries hinged on the efforts of open-side flanker Josh Turnbull who provided crucial support to keep both moves flowing.
Gatland believes that open-side flanker is one of the positions that Wales lack strength in depth and Williams' u-turn is a huge boost to the national side.
He hurt a rib in the Ospreys' loss to Stade Francais but lines up in a back-row with regional colleague Jon Thomas and Blues open-side Martyn Williams.
Bergamasco is a fine open-side with 69 caps to his name but his inexperience at number nine cost his side a try within two minutes of the kick-off.
The Glasgow pack drove their way to the Scarlets line before the ball was shipped smartly left for the open-side to go over from close range, Gregor converting.
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