Former Barcelona and Ajax star Frank de Boer says Chelsea are performing better than Manchester United this season because they are enjoying playing under their manager. 

Chelsea remain unbeaten in all competitions having won seven of of their nine games, and have adapted quickly to the new style of football brought in by Maurizio Sarri, who joined from Napoli in the summer.

United however have lost four times already, including twice in the last week against both Derby County and West Ham United.

A number of the club’s key players – most notably Paul Pogba and Anthony Martial – have also endured increasingly fractious relationships with manager Jose Mourinho, leading to speculation the Portuguese boss has ‘lost the dressing room’ at Old Trafford.

And De Boer says the difference in fortunes between the two sides can be accredited to the players’ happiness levels under each manager.

“Yeah that’s true (Sarri has changed the style quickly),” De Boer said on Sky Sports.

“They really like to enjoy the game. That’s maybe the difference between Manchester United and Chelsea.

“For me they are one of the favourites to go very far this season.”