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 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 by personally apologising to FA chairman David Bernstein for his tweet which described football's governing body as "a bunch of t****".
The footballer's outburst came after the FA's Independent Regulatory Commission was critical of his reliability as a witness in the John Terry racial abuse case.
The player has been charged with misconduct and has until Thursday to respond but his place in England's starting 11 does not appear to have been affected.
During the visit William and Kate met England manager Roy Hodgson and his squad on a training pitch at the St George's Park complex which aims to produce coaches and players to rival World and European champions Spain.
Household names like Wayne Rooney, Steven Gerrard and Frank Lampard broke off from a training session to chat to the royals who toured the 330-acre site for two hours. On a practice pitch, the Duke and Duchess shared a joke with Gerrard, captain of the England team which plays a World Cup qualifier match against San Marino on Friday.