Cristiano Ronaldo has denied claims that he has an obscene nickname for Lionel Messi.
In a new book about the Barcelona forward, it is suggested that the Real Madrid player routinely refers to the Argentine with an offensive expression.
Tensions between Ronaldo, 29, and Messi, 27, have long been rumoured.
"This is absolutely false and I have assured my lawyer takes action to sue those responsible," the Portuguese wrote on Facebook.
"I have the utmost respect for all my professional colleagues, and Messi is obviously no exception."
Ronaldo ended Messi's run of three consecutive Ballon d'Or victories last year.
Furthermore, the pair are split by just one goal in their bids to become the Champions League's all-time record goalscorer. The Barcelona man last week moved level with former Real Madrid striker Raul on 71 goals.
Messi needs just two more goals to become La Liga's all-time top scorer, having netted 250 times in 285 games and is one behind Telmo Zarra's record for Athletic Bilbao in the 1940s and 1950s.
Ronaldo is ninth on the league's leading scorers list. However, the Real forward has scored 18 this term compared to the Barca attacker's seven.