Romelu Lukaku has settled in very nicely at Manchester United since making the £75 million summer switch from Everton.

Six goals in as many games - including one against FC Basel in the Champions League last night - has represented a more than impressive start for the Belgian international.

Before the move, the 24-year-old's biggest critics doubted his ability to make the transition to a larger club with much higher expectations.

Not forgetting, the ex-Everton was also brought in to replace Zlatan Ibrahimovic - hardly the easiest boots, or shirt, to fill.

Shortly after his Old Trafford arrival, it was speculated Lukaku had called Ibrahimovic to discuss taking the Swede's old shirt number, No.9.

At that point in time, it wasn't clear whether Zlatan would be returning to the club after United decided not to extend his deal at the end of the previous campaign.

Of course, we now know he has signed a new one-year contract and is expected to be back in Jose Mourinho's plans once he fully recovers from the knee cruciate ligament injury he sustained in April.

Lukaku won't have to give up his No.9 shirt, though, as Zlatan will fill the vacant No.10 instead.

And Lukaku has finally opened up on what could have potentially been a very awkward conversation as Ibrahimovic granted him permission to wear the number nine.

"Yeah I did [call him about his shirt number] I didn't want to tell him I wanted the number 9," he said, as per The Mirror.

"But I called Zlatan and asked him and he said that I could take the number 9 and he would take the number 10.

"But I said to him I'm looking forward to you coming back because I know that you don't want to stop like this."

The prospect of Ibrahimovic and Lukaku lining up alongside each other at some point is one likely to excite Man United fans and terrify Premier League defences.

Ibra's comeback date is yet to be pencilled in and Mourinho has offered a cautious warning for the 35-year-old not to rush back into playing ahead of schedule.

"I think we need him. We wait for him, but with patience. He has to be patient," the Man Utd boss said after the 3-0 win over Basel on Tuesday.

"He doesn't have to be emotional and he doesn't have to try to make crazy things to improve [recover] quicker in his mind.

"Because I know that his desire is to improve quicker. So, calm – [take things] step by step."