Rowntree's instinct tells him Youngs is ready to mix with the big guns

Hartley's injury means young Leicester hooker gets an early chance to shine for England

Charlie Sharples gets ready for his second 'I'm desperate to start for England' (PA)

Graham Rowntree openly admitted yesterday that he was not entirely certain whether Tom Youngs, a molten-hot favourite to make his England debut at hooker against Fiji at Twickenham this weekend, is ready for the relentless rigours of international union. "Who can say for definite until they've seen him out there on the field, going up against the best players in the world?" asked the red-rose forwards coach. "At this stage, nobody can say they're sure about him."

But Rowntree, who knows what it is to play Test rugby at the sharp and painful end, is a man who trusts his instincts, and those instincts tell him that Youngs, thrust into the spotlight because of injury to the senior hooker Dylan Hartley, is more than capable of surviving – and, indeed, thriving. "From what I'm seeing of him, both in training with us and in the big games he's playing for Leicester, he's ready enough," he added.

Youngs, whose brother Ben is one of three scrum-halves in the England squad for this four-match international series against major southern hemisphere opposition, caught the eye playing for the midweek team on the demanding tour of South Africa in June. He did not, however, feature in any of the meetings with the Springboks and would still be on the outside looking in but for Hartley's knee problem and the long-term shoulder condition affecting the Bath forward Rob Webber.

"Dylan's injury has forced us to look at Tom as a possible starting hooker a bit earlier than we'd hoped," Rowntree admitted, "but I must stress that I have every confidence in him. One of the things I like about Tom is that he wants to scrummage – and as we know, two of the things a hooker must be able to do is throw to the lineout and scrummage under pressure. But he is able to do more than that. The dynamic things he does away from the set-piece areas put him ahead of other people."

Some of Youngs' recent lineout marksmanship has been a little on the wild side: no one in the Kingsholm crowd for the recent Premiership game between Gloucester and Leicester would have mistaken him for William Tell. But there is no disputing his ability with ball in hand, developed in a previous rugby life as a first-team centre. "There aren't many players capable of making such a radical positional switch," said Rowntree, admiringly.

Another player preparing to tread new ground at Twickenham is the Gloucester back Charlie Sharples, whose only international start to date was against France in Paris towards the end of last season's Six Nations. "To be part of an England team winning over there was a fantastic experience, but I don't think I made the most of that opportunity in personal terms," Sharples said yesterday. "It was a big chance for me because I'd been on the fringes for a while, but looking back it may be that I saw it as too much of a chance. It wasn't my best game."

Two of the forwards who started Tests against the South Africans in the summer – the Saracens lock Mouritz Botha and the Gloucester back-rower Ben Morgan – were released from camp last night as part of a 10-strong group not required for this weekend. Botha has lost his place in the match-day party to the uncapped Wasps youngster Joe Launchbury, while Morgan has failed to unseat the incumbent No 8, Thomas Waldrom of Leicester.

Others who missed the cut included the Northampton half-back Lee Dickson and the Wasps flanker James Haskell.