|Rugby World Cup: England v Wales|
|Venue: Twickenham, London Dates: 26 September Kick-off: 20:00 BST|
|Coverage: Live on BBC Radio 5 live and sports extra, BBC local radio, plus live text commentary on every match on the BBC Sport website.|
|Further coverage: BBC Radio Wales, BBC Radio Cymru, BBC Radio Scotland, BBC Radio Ulster and BBC Local Radio.|
Wales should start both Sam Warburton and Justin Tipuric as flankers against England in Saturday's World Cup game, says ex-Wales player Martyn Williams.
The 100-cap former open-side flanker expects Gatland to pick the "tried and trusted" trio of Dan Lydiate, Taulupe Faletau and captain Warburton.
But Williams said on Scrum V: "Could we go to Twickenham with two sevens? I'd go for it, I really would.
"It's so difficult to leave Tipuric out, he brings something extra to us."
Williams says creative Ospreys open-side Tipuric, 26, was "man of the match" in the two World Cup warm-up games against Ireland and their opening Pool A win against Uruguay on Sunday.
And he pointed to Australia's recent trend of also picking two specialist open-sides in David Pocock and Michael Hooper as an example of how such a partnership can succeed.
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But he admits Gatland has a major decision to make in the debate that revolves around Tipuric's creative ability and fellow Osprey Lydiate's defensive prowess.
Williams continued: "The Aussies do it with Hooper and Pocock, but the Aussies play a more expansive game than us so I think they can do that.
"Don't underestimate what Dan Lydiate does. He makes a lot of players look good around him.
"It's a massive call for Gatland. He singled out Tipuric and said how good a game he's had (against Uruguay)."
What else do you want from an open-side?
Worcester Warriors coach and former England number eight Dean Ryan says the choice facing Gatland will be made based on the tactics he hopes to employ.
Ryan said that it could be argued that Lydiate and Tipuric are not up against each other for a place in the starting XV because "in straight performance Tipuric is an extra man in the wide channel and he's had the highest number of turnovers".
Ryan asked: "What else do you want from your seven?
"I suppose the key debate for Warren is tactics. Does he want to take England on around the corner? With Lydiate you've got an extra ball carrier with Alun Wyn Jones going around the corner.
"But you're going straight into what is a traditional English strong point.
"And if you look to when England were beaten convincingly [30-3 in the 2013 Six Nations] at the Millennium Stadium, the two flankers were Tipuric and Warburton."
Gatland must assess injury concerns at centre, prop and full-back before naming his team on Thursday.