Guus Hiddink believes the success of Leicester City, Crystal Palace and Watford is testament to their organisation and the intensity of the Premier League.
Despite losing 1-0 to Liverpool on Saturday, Leicester lead the way at the top of the table. Claudio Ranieri's men are two points clear of Arsenal at the summit, with Palace and Watford currently keeping pace with European hopefuls.
By contrast, champions Chelsea are 15th, a full 13 points off the top four after Saturday's 2-2 draw with Quique Sanchez Flores' side.
And Hiddink concedes the Premier League's competitive nature will make it difficult for him to revive a flagging season at Stamford Bridge ahead of Sunday's trip to Manchester United - themselves struggling to find their best form
The Dutchman said: "First of all this league is very intense.
"The teams, even in December, who are competing for the top four, like Leicester City, like Crystal Palace, like Watford, it's not just by surprise.
"They are well organised, they have skilful players. You can be beaten by them."
Hiddink added: "We are going there [Old Trafford] and it will be difficult, but I hope this team will show in every game, away or home, the ambition that they showed [against Watford] in going for a win."