Ole Gunnar Solskjaer's team made two additions in the January transfer window after securing a permanent deal for Portugal global 67.2million much-anticipated transfer and 2019 Africa Cup of Nations Golden Boot victor on a five-month loan deal on Deadline Day from Shanghai Shenhua.
Meanwhile, he's played as the No.9 for his clubs since moving to the Chinese Super League in 2017.
Ighalo, who scored 16 goals in 35 games for Nigeria before retiring from worldwide football after winning the Golden Boot at the 2019 Africa Cup of Nations, was at Watford before moving to China but said joining United was a dream come true.
Ronaldo has played for Manchester United after joining the club in 2003. I probably should have gone through one of them, and we could have won! It has been insane, but I am happy to be in Manchester and this is a great opportunity for me.
"I haven't spoken to him, but, as soon as he signed, I knew we were playing against United pretty soon", said Cathcart. People who know me, even in Nigeria, and even when I played at Watford, my teammates knew I loved Man United, I supported them.
"I told my agent that "this is what I want".
"He said you'll get a cut in wages to go to United".
Ighalo has scored 16 goals in 34 global appearances for Nigeria, including five as top scorer at the 2019 Africa Cup of Nations.
"I should say, also, that I felt in China, he gave exactly the same effort and quality as he gave me four years ago. I want to follow his steps", he added.
"I know you'll know what we're talking about when you're done with football because I'm just so emotional, so I don't think too much about these things".
United will next be in action on Monday 17 February, when they travel to Stamford Bridge to face Chelsea, before taking on Club Brugge in the opening leg of their Europa League last-32 fixture.