Romelu Lukaku has matured already at Manchester United according to Roberto Martinez

The striker has made an impressive start to his Old Trafford career, scoring seven goals in as many games for the club since his £75m move - a feat that leaves him top of the Premier League goalscoring charts.

And Martinez, Lukaku’s manager at Belgium, played a key role in his development when he signed him at Everton in 2014.

He went on to score 87 goals in 68 games at Goodison Park before his record switch to the Red Devils, and Martinez knew the player would settle in at United with ease.

“It never crossed my mind that it would be something difficult for Rom,” he told Talksport.

"Everyone that plays with him or works with him realises very quickly that he has an elite brain.

“As a footballer, you can have your attributes but the focus he can have is quite unique. When he went to Manchester United he was solely focused on starting well and making a big impact and that is what he has done.

At just 24-years-old Lukaku still has his best years ahead of him, but Martinez believes he has already seen a newfound maturity in the player since joining United.

“He is still a very young player - sometimes we forget he is only 24,” he added.

“But his goalscoring record is sensational and he is a player that wants to carry on developing and carry on learning. Now he is with a manager with whom he will keep learning different aspects at club level.

“I have seen a big difference in terms of his maturity when he comes to international camps.

“From the young player I signed from West Brom and Chelsea at that time, it is the same goalscorer but with an incredible maturity. That is great to see and he still has many, many years to develop.”