The 22-year-old's stock has continued to rise over the past year thanks to an impressive campaign on loan at Crystal Palace, helping to earn him a place in Southgate's World Cup squad.
Loftus-Cheek is rumoured to be in line to make his first competitive start for England against Panama on Sunday, and Lampard is confident that the Blues academy product is more than ready to make his mark.
"Ruben is someone I know really well from when he was coming through the youth ranks at Chelsea," new Derby County boss Lampard told BBC Sport. "He is 22 now, but he probably came on to my radar when he was 15 because he was so highly spoken of.
"He would occasionally come and train with us in the first team from the age of 16, because he was that advanced. Straight away he made an impression because of his physical attributes, but he knew how to play too - he had great ability and even then he could drift past people on the ball.
"He does that even better now, with his pace and power when he is running at you, which makes him different from a lot of modern-day midfield players - and puts a fear into the opposition that they do not usually have. That is what he will bring to England's midfield against Panama, and his versatility makes him even more unique.
"Ruben is often used as an advanced midfielder, but he is neat and tidy enough on the ball to play as a link-man deeper in midfield. He can do both sides of the game, which makes him a great weapon for England boss Gareth Southgate to have, because having him on the pitch does not compromise the team in attack or defence."