Youngs is joined in the 23 by Wasps forward Joe Launchbury and Saracens prop Mako Vunipola, with Lancaster set to confirm his final selection on Thursday morning.
Dylan Hartley's injury-enforced absence means 25-year-old Youngs is almost certain to start in the front row and 2009 Lions assistant coach Rowntree is convinced he has what it takes to step up to the big stage, even if his promotion comes a little earlier than anticipated.
"You can't expect Tom to be the finished article from day one but the signs are he is going to be a very, very good player going forward," said Rowntree.
"You have to learn at the coal face and he is learning quickly.
"I refer back to Dylan Hartley as a young hooker for England and Steve Thompson. They were learning for long periods, throwing under pressure."
Youngs' journey to the top has been a remarkable one given that he began his professional career as centre and represented England at junior level in that position.
Former Leicester boss and now current Springbok supremo Heyneke Meyer suggested he switch to hooker and Youngs agreed, initially learning his trade at Championship outfit Nottingham before heading back to Welford Road.
And while his setpiece skills are understandably always under extra scrutiny given his past life as a back, Rowntree reckons his open-field skills, eagerness to learn and mental attitude will ensure he has a bright future in England colours.
"I have known Tom since he was in the Leicester academy and to make such a radical change in position is impressive. His performances are a stand-out," added Rowntree.
"You have to be able to throw and scrummage under pressure. The things he brings outside that, the real dynamic stuff, sets him ahead of other people.
"He has not had it all his own way in terms of the lineout. What impresses me is how he has recovered from setbacks within games. He is a strong character and will get stronger and stronger.
"Is he being pushed too quickly? I am not absolutely sure. The fact Dylan is injured means we have to look at him a bit earlier than we would have hoped to.
"But from what I am seeing the signs are he will pass the test at the top level. I have every confidence in him."
Revised England squad
Backs - Brad Barritt, Mike Brown, Danny Care, Owen Farrell, Toby Flood, Alex Goode, Ugo Monye, Charlie Sharples, Manusamoa Tuilagi, Ben Youngs
Forwards - Dan Cole, Tom Johnson, Joe Launchbury, Joe Marler, Tom Palmer, David Paice, Geoff Parling, Chris Robshaw, Mako Vunipola, Thomas Waldrom, David Wilson, Tom Wood, Tom Youngs
Players released back to their clubs
Anthony Allen (Leicester Tigers), Mouritz Botha (Saracens), Freddie Burns (Gloucester Rugby), Alex Corbisiero (London Irish), Lee Dickson (Northampton Saints), Phil Dowson (Northampton Saints), James Haskell (London Wasps), Ben Morgan (Gloucester Rugby), George Robson (Harlequins), Billy Twelvetrees (Gloucester Rugby)