Ighalo's temporary deal at Old Trafford is set to end on May 31 and although United have expressed a desire to keep the 30-year-old for longer, Shanghai have so far resisted all approaches.
Manager Ole Gunnar Solskjaer has been impressed with the Nigeria international, who has scored four goals in eight appearances, but is said to be "relaxed" about the situation because Marcus Rashford is almost fully recovered from injury.
Ighalo was brought in during the January transfer window as emergency cover for Rashford, who last played a game on Jan. 15 because of a back problem, and sources have told ESPN that the deal did not include an option to buy.
The former Watford man wants to stay at United, his boyhood club, but Shanghai appear set on having him back for the start of the Chinese Super League campaign in June.
The original agreement with Shanghai would have covered the end of the season but with the campaign postponed because of the coronavirus pandemic, Ighalo is set to miss United's remaining nine Premier League games and the culmination of the FA Cup and the Europa League.
Despite Rashford's return to fitness, Solskjaer is still keen to add another striker to his squad in the next transfer window. Anthony Martial has been deployed as the central striker for much of the season but Solskjaer wants more options and will press ahead with a revamp of his forward line.
The Norwegian has been kept informed of the financial implications of the COVID-19 outbreak -- which has already cost the club more than £20 million -- and although executive vice-chairman Ed Woodward has insisted the market will not be "business as usual," Solskjaer will still be given money to spend.