Brazilian forward Robinho could be a doubt for the visit of AC Milan's Champions League last 16 opponents Atletico Madrid next week after suffering a thigh knock on Saturday.

Robinho was replaced for the second half of Milan's 3-1 defeat to Napoli by compatriot Kaka and is set to undergo further tests on a left thigh injury.

An official statement by Milan said: "AC Milan communicates that during the Napoli-Milan match, Robinho suffered a muscular injury in his left thigh.

"The Brazilian striker will undergo further tests next week."

Italian media reports claim Robinho will miss Friday's home game against Bologna and that he is a major doubt for the visit of Atletico on February 19.

Milan's latest defeat left them 11th in Serie A, seven points behind city rivals Inter who occupy the last available Europa League qualifying spot and 18 behind Napoli in the final Champions League qualifying position.