Argentina coach Diego Maradona says his son-in-law, striker Sergio "Kun" Aguero, should leave Atletico Madrid if the club does not invest.

"To make the best of Aguero's qualities they must create a team worthy of him and sign some players," Maradona said in an interview published in Saturday's Marca sports daily.

"Otherwise they must let him go and not harm his development."

Argentine international Aguero, 21, is a star turn with Atletico, for whom he signed in 2006 from Argentine side Independiente. His contract runs to 2012.

Atletico came fourth in La Liga last season to reach the Champions League but this season their form has been dismal and they are out of the Champions League already and also in the relegation zone.

Aguero was to sit out Saturday's friendly international with Spain at Atletico's Vicente Calderon ground owing to injury.

Maradona meanwhile repeated earlier assertions that he rates his country's own Leo Messi more highly than Real Madrid's Cristiano Ronaldo.

The latter "did incredible things with Manchester (United) but Messi wreaks more havoc. The ball is stuck to his foot!"