Marco Verratti and Ivan Perisic were once booked for heading the ball back to their goalkeepers

Marco Verratti and Ivan Perisic were once caught out by a law they didn't even know existed, resulting in a yellow card for both players.

In separate matches for Paris Saint-Germain and Inter Milan, Verratti and Perisic were booked for using 'trickery'.

Verratti and Perisic deliberately headed the ball back to their goalkeepers, which was considered a foul - with an indirect free-kick awarded.

In a league fixture against Nantes, the Italian midfielder had the ball at his feet but opted to give possession to Kevin Trapp.

He got on his hands and knees before heading the ball back to the German keeper.

However, Verratti was booked for his unorthodox back-pass.

The same thing happened to Perisic against AS Roma. Unlike Verratti, the Croatian winger kicked the ball up in the air then headed the ball to Samir Handanovic.

The match referee immediately blew his whistle and branded a yellow card to Perisic, who couldn't believe the decision.

But, according to the laws of the game, players are not allowed to use 'trickery' in order to get around Law 12.

"No trickery may be used to get around the terms of the amendment to Law 12," the rules state.

"A player may pass the ball to his own goalkeeper using his head, chest, knee, etc.; however, if, in the opinion of the referee, the player uses a deliberate trick - such as flicking the ball to his head with his foot and heading it to the goalkeeper or kneeling and deliberately pushing the ball to the goalkeeper with his head or knee - he must be cautioned for ungentlemanly conduct.

"It makes no difference whether or not the goalkeeper touches the ball with his hands; the offence is committed by the player who is seeking to circumvent both the Spirit and Letter of the Law."

International Football Association Board's (IFAB) website states an indirect free-kick should be awarded if a player 'initiates a deliberate trick for the ball to be passed to the goalkeeper'.

Point 12.2 says: "Initiates a deliberate trick for the ball to be passed (including from a free kick or goal kick) to the goalkeeper with the head, chest, knee etc. to circumvent the Law, whether or not the goalkeeper touches the ball with the hands; the goalkeeper is penalised if responsible for initiating the deliberate trick."