Ireland captain Rory Best says Kieran Marmion has had to bide his time behind Conor Murray in the international pecking order, but says now is his chance to deliver.
Bruising on the shoulder has meant Joe Schmidt must plan to stop England’s quest for a Grand Slam minus one of the key cogs in the team, but Marmion has shown glimpses in his 13 appearances to date that he has what it takes to cope at Test level in what will be his first Six Nations start.
Captain Best insisted the Connacht half-back is ready for the challenge.
"It is a massive day for him," he said.
"You just have to look at the way he's performing, not just last season, but this season for Connacht - this is something he deserves.
"He is very unlucky he is behind a real world-class nine.
"It is his day. We always talk that you get your opportunity along the line through someone else's misfortune. Well, his opportunity has come now."
Ireland will be aiming to stay inside the top-four world-ranking berths after this weekend, in order to remain in the first pot ahead of the World Cup pool draw in May.
Wales could still sneak into the top four with a win over France in Paris on the Six Nations' final weekend, while England would stay second in the world with what would be an historic win in Dublin.
Live Six Nations coverage of Ireland v England on RTÉ Two and RTÉ Player (KO 5pm), live radio commentary on RTÉ Radio 1’s Saturday Sport and live blog on RTÉ.ie and the RTÉ News Now app.
Television coverage begins at 12pm on Saturday with live coverage of Scotland v Italy (KO 12.30pm) and France v Wales (KO 2.45pm) on RTÉ Two and RTÉ Player on Saturday.
Live coverage of Ireland v England in the Under-20 Six Nations on RTÉ Two from 5.30pm (KO 5.45pm) on Friday.
Live coverage of Ireland v England (KO 8pm) in the Women’s Six Nations on RTÉ Two and RTÉ Player from 7.50pm on Friday.