The Polish goalkeeper has taken a stunning swipe at the Barcelona forward in his new book.
Although Lionel Messi is widely regarded as the best footballer on the present, the Argentine also has a squeaky clean image, with the Barcelona man seen as holier than thou.
The Camp Nou hero is regularly praised for his attitude and professionalism, with the South American seen as a fair player.
Exerts of the Polish stopper’s books have been published in the Spanish press, with the author not holding anything back.
Dudek has claimed that during his time in the Spanish capital he witnessed and heard from his team-mates of Messi swearing on the pitch.
The retired stopper called Messi “false and provocative” according to El Confidencial, while claiming his former team-mate Cristiano Ronaldo was “arrogant but underneath an authentic type.”
Dudek went on to slate Barcelona during the time when Pep Guardiola was head coach, stating that it was them, not Madrid, who were responsible for inciting the unsavoury nature of the clubs’ clashes.
"Pep Guardiola lives for provocation," Dudek continued.
"Pepe and (Sergio) Ramos told me they couldn't believe a guy (Messi) with an image of being quiet and seemingly good, could be full of such profanity. Like Messi, the Barca of Guardiola lived for provocation.”
Messi is the frontrunner for this year’s Ballon d’Or award and has already led Barcelona to a domestic double.
The Argentine star will feature in Saturday’s Champions League final against Juventus, with the Blaugrana looking to sow up an incredible treble.