The Red Devils have been in decent form so far this season and look as if they will be Manchester City's closest challengers for the title.
United legend Ferdinand urged Lukaku to 'fight' Ibrahimovic for a place in Jose Mourinho's starting XI.
But in the cold analysis of football, whether a lad can sing and dance, enjoy a full and happy social and family life or have 4million followers on Twitter, it's neither here nor there. It might be that Lukaku is forced to raise his game to compete with the experienced 36-year-old. He is a substitute, an option, in theory only.
"Romelu Lukaku faces a new reality now that Zlatan Ibrahimovic is fit", he told The Times.
The Spaniard tweeted a photo of the pair chatting, along with the caption: "Sometimes 'God' also talks to humans". "We believe we can do it".
GETTYRomelu Lukaku is still Manchester United's top striker says Jose Mourinho
United travel to Switzerland to take on FC Basel tonight in the Champions League needing a draw to confirm top spot in Group A.
And he's a valued member of the dressing room, too, with David de Gea just posting a tweet which highlights how much Man United's players love Ibrahimovic. What is more obvious that their returns will make an impact.
"But because of this level of player, they understand the game, they know how to give the information to the youngsters". Were it not for third-choice goalkeeper Joel Pereira, Shaw would be bottom of the list.
Ibrahimovic has always been a controversial figure throughout his career and it would come as no surprise if he does end up getting involved in a rift with his Belgian team-mate.
Ibrahimovic returned to fitness after seven months out with injury in the same game. Against Newcastle it was like he hasn't been injured for a month, he brings such big quality, a different quality and I bring experience and mine.
Chris Smalling continues to get a chance to prove England boss Gareth Southgate wrong, and is partnered by Marcos Rojo, over the ever scrutinised Victor Lindelof. But the fact that he is gradually slipping out of the public and punditry consciousness is worrying.