Managers have today been given the green light to send on substitutes with tactical notes to hand to team-mates.
While Chelsea have been credited with revamping the Premiership since Roman Abramovich's arrival in 2003, boss Jose Mourinho may have started a new trend
with his messaging system to players during games.
In Saturday's clash at Everton on Saturday Mourinho sent on Czech Republic international Jiri Jarosik in the 72nd minute with a note that was handed on to Portugal midfielder Tiago.
The tactic worked with the Barclays Premiership leaders holding on to win 1-0 at Goodison Park.
Referees chief Keith Hackett revealed Mourinho's tactics did not break any rules of the game and will not face any further action as his actions did not put any players in danger.
Hackett, who is head of the Professional Game Match Official Limited, said: "Effectively there's nothing in the laws that prevents it happening.
"It does not constitute a danger any more than people being in the technical area.
"They (Chelsea) have been a little more sophisticated and a little different. The Football Association were aware of it, and it's legal."
Hackett joked: "If he were to take a Christmas hamper onto the pitch it may be a different matter."