Manchester United have sent scouts to watch Napoli center-back Kalidou Koulibaly as they plan a mega bid in January, according to reports.

Jose Mourino’s men have already conceded as many goals this season than they did in the whole 2017/18 campaign.

They sit a shocking 19 points behind Premier League-leaders Liverpool after a 3-1 loss at Anfield on Sunday.

And according to The Sun, the club are planning to bring in Koulibaly to help turn their fortunes around in January.

It is understood Red Devils scouts were at Anfield for Napoli’s 1-0 defeat to Liverpool in the Champions League last week.

An Old Trafford source said: “The club had people there and it wasn’t just to run the rule over Liverpool.

“They wanted to see what Koulibaly was like against English opposition after watching him a few times in Italy.

“He impressed everyone and the need for players at the back has never been more evident.”

The 27 year-old, widely considered to be one of Europe’s best defenders, is likely to cost up to £90m.

Chelsea manager Maurizio Sarri, who previously managed Napoli, reportedly tried to lure him to Stamford Bridge during the summer, but instead Koulibaly signed a new five-year deal with the Serie A club in September.