has claimed former team-mate Ryan Giggs would be worth £2billion in today's "mind-boggling" transfer market as clubs rake in massive fees for "average" players.
The Republic of Ireland assistant manager admitted his surprise at some of the figures which have been paid this summer, with Paris Saint-Germain forking out a staggering £200million for Neymar and preparing to invest heavily once again in Monaco's Kylian Mbappe.
However, it is the prices which have been paid for players lower down the food chain which have surprised Keane.
He said: "It's mind-boggling, the figures that are out there - especially for the average players.