Many believed that Romelu Lukaku to Chelsea was a done deal throughout this summer.

With Antonio Conte telling Diego Costa that he was no longer needed at Stamford Bridge, it seemed inevitable that it would be Lukaku returning to the club to replace him.

However, Manchester United had other ideas.

Jose Mourinho has managed to convince the Belgian striker to turn down the Premier League champions and sign for the Red Devils in a £75 million deal.

But why did Lukaku choose United over Chelsea?

Lukaku to join 'the biggest club in the world'

Well, firstly, the forward revealed he was delighted to join ‘the biggest club in the world.’

"It's the biggest club in the world. It's a club that's hungry to win the league again, to be dominant in the world again and the sort of opportunity I always wanted since a child," he said in his very first interview.

The Mourinho factor

Then there was the role Mourinho played, despite the Portuguese boss selling him whilst at Chelsea in 2014.

"[Mourinho is] a guy who I wanted to play for since I was 10 years old, so now to have the opportunity to work under him again is great," Lukaku added.

"We've been in contact. He explained to me how the club was like, what he expects from me.

"You know, we were together under different circumstances. Obviously, the first time when I met him, I was still a young kid, and I was eager to play. And he understood my decision why I left at the time."

Agent Pogba

But there was a third factor that secured the deal.

In recent weeks, Lukaku has been on holiday with United midfielder Paul Pogba in Los Angeles. After the club revealed that they had agreed a fee with Everton, Pogba uploaded a video of the pair discussing the impending transfer in their luxurious villa in Beverly Hills.

And Lukaku has now revealed how Pogba convinced him to sign for the club.

"I’ve been talking to [Pogba] for about seven or eight years. And now he’s living in Manchester," he said.

"I live in Manchester. He lives like down the road from where I live, so we’re together on a daily basis.

"He was explaining to me how it went at the club, and it triggered something in my head. When the opportunity came, I didn’t have to think twice. I’m really excited."

So it seems Pogba’s hashtag #AgentP is actually very true. The Frenchman has worked his magic and convinced Lukaku to sign for United, rather than Chelsea.

That’s one way to pay back your £89 million transfer fee.