Juventus forward Cristiano Ronaldo has been described as "a failure" and a "big problem" by former Real Madrid and Italy striker Antonio Cassano.

Juve lost on away goals to Porto in the Champions League earlier this month, meaning that the Italian giants have fallen at the last-16 stage of the tournament in both of the past two seasons.

Speaking to Corriere dello Sport, Cassano said: "Juventus signed him to win the Champions League, but they've done worse with him than they've done before.

"They'd also won the Scudetto without him. I think he's been a failure."

Ronaldo was also blamed for having a major role in the exits of former Juventus managers Massimiliano Allegri and Maurizio Sarri.

"Juventus got rid of a coach (Allegri) who, in the last 20 or 30 years, has produced the best football in Italy and his big problem was one: Cristiano Ronaldo. It was for Sarri and it is for [Andrea] Pirlo," Cassano added.

The 36-year-old five-time Ballon d'Or winner has 30 goals in 34 appearances in all competitions for Juve this season.

However, the Old Lady currently sit fourth in the Serie A table, 10 points adrift of leaders Inter Milan and with their nine-year reign as champions looking likely to come to an end.