Romelu Lukaku claims an impressive 4-0 victory over West Ham is "just the start" after Manchester United made a statement of intent in their opening match of the Premier League season.

The striker, signed from Everton for a reported initial fee of £75million in July, promptly began to repay that sizeable investment with a brace on his competitive Old Trafford debut, substitute Anthony Martial and Paul Pogba striking late on to send United to the top of the table at the end of the opening weekend.  

It remains to be seen if United, who won the League Cup and the Europa League in Jose Mourinho's first campaign in charge last term, can improve on a sixth-place finish by challenging for the title this time around. 

Lukaku, though, is full of confidence in the potential of both the Portuguese boss and his new team-mates. 

He told Sky Sports: "It's just the start, the manager has a plan, we will try to follow it and hopefully it will take us somewhere.

"To play well in front of such a crowd [is pleasing]. The most important thing was the win. We started well and have to keep working hard

"[I am] just [happy] for the team, when you play for Manchester United the job is to score goals. Everyone created a lot of chances and we scored a lot of goals. 

"He [Mourinho] wants me to be a leader for team, in training we work really hard, [and] the hard work will pay off.

"The fans want to see attractive football, that's what we did, the crowd was very pleased."

Matic, another off-season recruit from Chelsea, also impressed at the base of midfield, completing a timely interception to trigger the counter-attack that led to the first goal. 

"It was a really important game for us to start well and win the three points against a good side," he told Sky Sports. 

"They [West Ham] were very compact, but there was more space after the first goal.

"I am very happy for the team, we started well and will take the three points. [In the] next game we will start with more confidence."

Asked if he has been purchased to allow Paul Pogba, scorer of United's fourth in injury time, to get forward more often, Matic replied: "No, he [Mourinho] said I have to do my job and he [Pogba] has to do his job. 

"Not only Pogba [had] a good game, everyone played very well. 4-0 against a good team, we have to continue to work like this, to play like this."