Defending Premier League champions Chelsea have struggled for form at times this season.

Antonio Conte's side are third behind the two Manchester clubs and have already lost four times - to Burnley, Manchester City, Crystal Palace and West Ham. 

The Blues have progressed to the knockout stages of the Champions League, but face a tough test against Barcelona after finishing second in their group behind Roma. 

To make matters worse, it's suggested that Conte has clashed with defender David Luiz, who was a key part to Chelsea's title success last season. 

The Brazilian has rarely featured since falling out of favour after the 3-0 defeat away to Roma in October. 

Conte insists Luiz hasn't had any game time in the Premier League due to a knee injury, but the 30-year-old has been heavily linked to Real Madrid and Juventus over the last month. 

The replacement

Perhaps already planning for the defender's exit, the Chelsea boss reportedly has his eye on a world-class replacement and wants to make a bid in January. 

According to the Mirror, the Italian wants to sign AC Milan's Leonardo Bonucci, who he knows very well.

The defender played under Conte for three years at Juventus, as well as regularly in the Italian national team for another two. 

Bonucci's struggles

Despite being one of the highest rated defenders in Europe, Bonucci has struggled with Milan this season. 

He left Turin for over £37 million last summer after falling out with manager Massimiliano Allegri but hasn't been able to inspire his new side. 

The club are currently eighth in Serie A, already 18 points behind leaders Napoli. Champions League football next term also looks like a distant dream after much expectation earlier this year.  

And following an embarrassing 3-0 defeat to Verona at the weekend, Milan players have been ordered to stay at their training camp before an important fixture against Atalanta. 

With morale low and performances poor, Chelsea could offer a welcome exit door for Bonucci, just six months after he moved to the San Siro.