The 30-year-old's loan from Shanghai Shenhua expires on Monday, and the Chinese Super League club want him back for their new campaign.
Shanghai have offered the Nigerian a three-year extension worth £480,000-a-week.
But the Daily Star says the club's chairman Wu Xiaohui has told Ighalo he will change that figure if he decides to stay at United.
Ighalo will be allowed to stay until January at United, but his new deal at Shenhua would be worth £400,000-a-week.
But the money doesn't matter to the striker, who is living out his dream playing for the Red Devils.
Both clubs are in talks over the extension and must come up with a solution before Monday.