The 30-year-old sealed his dream move on Deadline Day, when moving to Old Trafford on loan from Shanghai Shenhua.
But the Nigerian suffered the personal tragedy of losing his older sister back in December.
Ighalo revealed in a tribute to her that she died at the age of 42 on December 12 last year.
The former Watford striker has kept the details of her passing private, but was clearly close to his sibling.
He has posted a series of pictures of them together on social media, and he has made an image of Mary his profile picture on both Twitter and Instagram.
And he has posted a picture of a brand new pair of bright red Nike football boots, featuring her name written just above the trademark swoosh.
Following her name, Mary Atole, is the Nigerian flag.
Ighalo captioned an image of the boots with the message: “MARY ATOLE (nee ighalo) lives forever 12-12-19”.
Having last played for Shanghai Shenhua on December 1 in a 3-0 defeat to Chinese champions Guangzhou Evergrande – Ighalo has not taken to the field since his sister’s passing.
It will be fitting that on his first opportunity to pay tribute to her on the pitch, he will do so wearing the colours of Man United – the club that he grew up dreaming of playing for.
While he is not thought to be 100 percent match fit, United’s mini winter break means that they do not have a game until travelling to Stamford Bridge to face Chelsea on February 17.
If that comes too soon – Ighalo could debut the new boots at Old Trafford against Club Brugge in the Europa League the following Thursday.
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