Jose Mourinho said Romelu Lukaku needs a new boot deal in order to get back among the goals as the Manchester United manager jokingly blamed the striker's struggles on his footwear.

Belgian star Lukaku, 24, fired another blank in United's entertaining 4-2 win over Watford in the Premier League on Tuesday.

The £75million signing from Everton wasted a gilt-edged opportunity in the second half as he was left with just one goal in his past 11 matches in all competitions for United.

However, Mourinho – after joking about Lukaku's form – heaped praise on the Belgium international, who has scored 12 goals this season.

"I think he needs a big contract with boots," Mourinho told reporters.

"At the moment, he has no contract with any brand, that is why he is wearing black boots! He needs to be paid the right money so he goes back to goals.

"Jokes apart, he works amazingly well for the team. I would never blame him for missing an easy chance, never.

"He's an amazing professional. I couldn't be happier with him."