The Duke of Cambridge made light of England defender Ashley Cole's twitter outburst attacking the Football Association when the two men met at the opening of a soccer centre of excellence.
William called the Chelsea player a "naughty boy" for the offensive tweet he posted last Friday, strongly criticising football's governing body.
Cole was left laughing on Tuesday following the comment made when the Duke and Duchess rubbed shoulders with the England squad as they toured the FA's £105 million St George's Park, near Burton upon Trent, Staffordshire, before opening the facility.
The Times reported that William had apparently smiled at the Chelsea defender, shaken his hand, and told him: "If you continue to be a naughty boy, they will take your Twitter account off you."
As the FA's president William is part of the body's senior hierarchy and so could have taken offence but appears to have seen the humour in the situation.
Cole attempted to draw a line under the matter last night by personally apologising to FA chairman David Bernstein for his tweet which described football's governing body as "a bunch of t****".
The royals, making their first set of public appearances since the furore which surrounded the publishing of topless pictures of Kate Middleton, were on good form as they chatted to Roy Hodgson's England squad before being given a tour of the £100m complex.
England face San Marino at Wembley on Friday before travelling to Poland for their fourth World Cup qualifier next Tuesday.