Tuilagi, 20, and Sharples, 21, were singled out for praise by manager Martin Johnson after surviving the first cut of the England training squad.
Johnson has confirmed that Joe Worsley, Thomas Waldrom, George Chuter, David Strettle and James Simpson-Daniel had all been released from the original 45-man party.
For that quintet, the World Cup dream looks over.
But Sharples and Tuilagi are now vying to make their Test debuts in England's back-to-back internationals against Wales over the next fortnight.
Johnson will make the final cut on August 22 when he finalises his 30-man World Cup squad.
"We were confident they were worth their place or we wouldn't have picked them. They've got this far, which shows we've been pleased with what they've done," said Johnson.
"The next step will be selection and getting on the field in the next two weeks."
Tuilagi has impressed the England management - and his new team-mates - since his promotion to the senior squad after being named Aviva Premiership young player of the year.
The Leicester centre, whose four elder brothers have all played for Samoa, capped an impressive performance in last Thursday's internal trial match with a try.
Sharples, one of the starts of June's Churchill Cup, was a late inclusion in the original squad as cover for Chris Ashton, who had just undergone a knee operation.
The Gloucester wing has leapfrogged Strettle and Simpson-Daniel in the pecking order and was today described as "the fastest white guy I have ever seen" by full-back Ben Foden.
Johnson continued: "I've been impressed (by Tuilagi). He's a strong, powerful young man. He is an incredibly impressive physical specimen.
"You saw the quality of Manu last season in the Premiership and I think he's improved just being in this environment here, like all these guys do.
"He's worked very, very hard and he's just got better and better.
"He has come in from a very good club, understanding what it is to be a professional player and work hard and prepare - like Charlie Sharples and like Tom Wood when he came in (during the Six Nations).
"(Sharples) is a very impressive young man who has worked very hard. He's got his head down and taken it all in.
"He's very thorough in what he does - he's an impressive lad who has taken that next step, as 40 of them have."
Johnson will name his side for Saturday's Investec international at Twickenham on Thursday but he is likely to be without Courtney Lawes and Ben Youngs, who are both injured.
Chuter's departure leaves England with three hookers in Dylan Hartley, Steve Thompson and Lee Mears - all of whom are now likely to travel to New Zealand.
The decision to cut Worsley and Waldrom, who has been struggling with a calf injury, leaves Harlequins captain Chris Robshaw and Sale flanker Hendre Fourie in contention for World Cup selection.
"These (warm-up) games are the only time in your England career when there is a bigger picture. The players know what is at stake.
"There are still 40 players here and they all want to play well - but the best chance of doing that is as a group and not as individuals."
Waldrom has been struggling with a calf injury and has not trained for the past fortnight while Worsley has missed out on the chance of playing at a fourth World Cup, having made his Test debut in the 1999 tournament.
Strettle is arguably the biggest casualty, having been in England's 22 for their final RBS 6 Nations Tests against Ireland in March.
"Thomas had an injury to his calf that meant he wasn't able to train at all in the last two weeks. The other decisions were very tough because everyone has contributed massively," said Johnson.
"It was particularly tough on Stretts (Strettle) who has trained very well and did everything we asked of him.
"Joe has come back from some injuries last year, worked incredibly hard to get back in but just came up a bit short right now."
Foden and Chris Ashton today officially launched England's new all black change kit, which they will wear for the first time against Wales on Saturday and in their opening World Cup match against Argentina.
The RFU's decision ruffled a few Kiwi feathers, not least those of prime minister John Keys and former All Black Jonah Lomu.
Ashton, who scored a magnificent try when England beat Australia in their grey change kit last November, laughed off the controversy.
"You are more worried about playing for your country than what colour kit you are wearing. If we played in pyjamas it wouldn't bother me," said the Northampton wing.
"The grey one worked well - we played well in it - let's hope it is the same with the black one."
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