When you win the Premier League, the last thing a club can afford to do is stand still.

Despite pressure from Spurs, Chelsea were relatively comfortable Premier League champions last season and Antonio Conte's debut campaign in charge could not have gone much better.

However, now that the summer has arrived, plenty of the other top six clubs in England's top-flight have been making big moves in the transfer market.

Chelsea, have not.

Although Diego Costa looks set to leave after being told he is surplus to requirements via text message, his likely replacement, Romelu Lukaku, is yet to return to Stamford Bridge.

The lack of activity is said to be angering Conte and the board are hardly happy with him for how he handled the Costa situation either. The leaking of that text message significantly decreased their negotiation power with other clubs when it comes to the Spanish international striker.

Now that club legend John Terry has left on a free transfer, it looks as if Conte is looking to raid Serie A for his replacement.

Chelsea have reignited their interest in Napoli centre-back for Kalidou Koulibaly and according to The Sun have made a £52.5million bid.

The 25-year-old has been excellent for the Italian heavyweights in recent seasons but it is believed the Naples club don't want to part with another prized asset after losing Gonzola Higuain last summer, especially because they feel they are close to beating Juventus to the Serie A title.

Does Conte really need Koulibaly? Of course, he's a top draw player, but the young trio of Kurt Zouma, Nathan Ake and Andreas Christensen are all waiting for their chance in the first team and have more than enough potential to thrive.

Conte clearly does not want to take that chance and with Lukaku's move stalling over Everton's £100 million price tag, the Italian is looking to get the ball rolling in other areas before the Blues fall behind their rivals in the market.

Chelsea clearly have the money, but how far are they willing to go to secure their targets? With Champions League football next year, they need more bodies.