Argentina coach Alejandro Sabella believes strict refereeing in Spanish club football has allowed Lionel Messi to flourish into the world's best player.

The three-time Ballon d'Or winner is undoubtedly the greatest player of his generation but the debate - largely fueled by the Argentinean's shortcomings with the national team - on whether Messi is the greatest of all time continues to rage on.

On 20 March 2012, Messi scored three goals for Barca in a win against Granada to surpass Cesar Rodriguez's mark of 232 goals to become the club's leading scorer. In contrast, Messi currently averages a goal in every three games for Argentina.

"In Spain the referees are stricter with physical play. In contrast, in South America they are more permissive," Sabella told Radio Sport Telam.

"If you play there [in Spain], there are more yellow and red cards and that is why Messi is better in Spain than when wearing the Argentina shirt.

"The best thing is that Messi is Argentine because he is a true ambassador of our country. He helps us on the field and makes us look good off it with his exemplary behaviour."

However, Sabella was keen to stress that the obvious qualities of Messi at club level should not be overshadowed by his comparatively lesser achievements on the international stage. In fact, Sabella says that Messi is so good that The Royal Academy of Spain - an institution responsible for regulating the Spanish language - should invent a new word to describe the player's talent.

"The Royal Academy of Spain should invent a word to define him [Lionel Messi] exactly. For me, as his coach, it is a privilege to direct him," Sabella said.

On Tuesday, Messi became the outright holder of the record for most goals in a single UEFA Champions League campaign after scoring the first of his two penalties in Barcelona's 3-1 quarter-final triumph against AC Milan.

Messi's current haul of 14 goals beat Ruud van Nistelrooy's previous tally of 12 goals registered back in 2002/03 for Manchester United.