Peter Moores has been named England's new National Cricket Academy coach and takes up the post on 1 October.
Aged 42, Moores is some 15 years younger than Marsh
Currently the Sussex director of cricket, the 42-year-old's CV includes leading the county to an unexpected success in the Championship in 2003.
He has signed a three-year deal and succeeds Rod Marsh who is returning to Australia after four years in the post.
Moores said: "I am thrilled to have been given the chance to build on the foundations laid by Marsh."
He beat off competition from a number of well-known candidates believed to have included Worcestershire coach Tom Moody, former England captain Mike Gatting and England assistant coach Tim Boon.
Moores added: "It's a huge wrench to leave Sussex after all that we have achieved in recent years.
"My immediate priority this season will be Sussex but my long term vision for the academy will be based around the same ethos that has operated at Hove - one which involves plenty of hard work and careful preparation.
"It's a terrific opportunity for me to work with quality individuals and play an important part in the development of the next generation of England players."
Former Australian Test wicket-keeper Marsh announced in December he would be stepping down in September to return to Australia to be with his grandchildren.
Moores will be expected to guide the next generation of international cricketers with a clear objective that 95% of England's cricketers will have been through the academy by 2007.
Several members of the current England squad have been through previous academy intakes.
The most celebrated graduates are batsman Andrew Strauss and paceman Steve Harmison.
Popular all-rounder Andrew Flintoff also spent a brief spell at the academy, while James Anderson and Robert Key are others to have come through the system.