According to the The Sun, United had already put out feelers for the former Watford striker, who is playing in China for Shanghai Shenhua.
Ighalo would return to the Premier League – even for a short-term deal – if the numbers can be agreed.
Two other interested clubs report that Ighalo is now waiting on that dream move to United becoming possible.
United manager Ole Gunnar Solskjaer is desperate to land a striker before the transfer deadline closes this evening.
The injury to Marcus Rashford has left United strikeforce looking threadbare heading into the final few months of the campaign.
Solskjaer was recently snubbed by compatriot Erling Haaland who signed for Borussia Dortmund ahead of United.
Uruguayan striker Edinson Cavani has also been linked with a move to United this month as he tries to force through an exit from Paris Saint-Germain.
Ighalo made a name for himself during his three years with Watford.
After joining in 2014, initially on loan, he powered the Hornets to promotion in his first season at Vicarage Road.