WATFORD, United Kingdom: Manchester United manager Jose Mourinho is confident Romelu Lukaku's problems in front of goal will come to an end -- just as soon as he secures a new boot deal.

Lukaku laid on a goal for Anthony Martial in United's 4-2 win at Watford on Tuesday, but squandered three good opportunities and has now scored just once in his last 11 appearances.

The Belgium striker is playing in plain black boots because he is currently between boot contracts and Mourinho joked the goals would start flowing again once he had found himself a new deal.

"I think he needs a big contract with boots because in this moment he doesn't have a contract with any brand," Mourinho told journalists at Vicarage Road.

"That's why he's playing with the black boots. He needs a brand to go there and give him the right boots and pay him the right money, so he goes back to (scoring) goals.

"But jokes apart, he works amazingly well for the team. I would never, never blame a player like him for an easy chance that he missed. Never.

"With me he knows he that doesn't have that pressure. Amazing player, amazing professional, great ambition, great colleague. I couldn't be happier with him."

One player who had laced up his shooting boots was Ashley Young, whose brace against his former club set United en route to a win that left them five points below Premier League leaders Manchester City.

He opened the scoring in the 19th minute with a crisp effort and then left Mourinho open-mouthed in the United dug-out with a magnificent 25-yard free-kick that curled into the top-left corner.

"I was surprised that Paul (Pogba) gave him permission. I was not surprised with his shot," said Mourinho, explaining his reaction.

"He's playing well. I know what he can do for us, all the positions he can be useful for us.

"This left-back position I think is adapted to him and probably in this stage of his career, where he has the maturity and the tactical experience, it's good. He's playing really well."

Silva rues Rojo let-off

Martial's goal put United 3-0 up after 32 minutes, but Watford struck twice late on through substitute Troy Deeney and Abdoulaye Doucoure before a Jesse Lingard solo goal settled the visitors' nerves.

Mourinho, who claimed his side could have scored "seven or eight", said Watford's second-half revival should stand as a warning to his players about never easing up.

"I think we had mistakes in the box and that cost us two goals," said the United manager, who takes his team to fourth-placed Arsenal on Saturday.

"Maybe it's a good lesson and it's good to have lessons without losing points, so the next time you are winning 2-0 or 3-0, I think the players will remember that football is football."

Watford head coach Marco Silva took issue with his Portuguese compatriot Mourinho's suggestion United could have won by a landslide.

"I think it seems harsh for everyone," he said. "It's Jose's opinion. I didn't see the same game."

Deeney's goal, on his return from a three-game ban, arrived from the penalty spot in the 77th minute after a rash foul on substitute Roberto Pereyra by Marcos Rojo.

Centre-back Rojo had been booked in the first half and Silva was aggrieved that referee Jon Moss elected not to show him a second yellow card.

"When we scored the first goal, we were already better," said Silva, whose side remain eighth.

"We scored the penalty and at that moment it looked like a second yellow card for Marcos Rojo. If it's 11 against 10 it would be very difficult for them.

"It was difficult anyway because we scored the second, but if it's 11 against 10 it would be even better."-AFP