The Nigerian has already made a personal plea to Shanghai Shenhua to let him finish the season at Old Trafford, before returning to China.
BBC Sport says talks between United and Shanghai are continuing but the clock is ticking ahead of Sunday's deadline.
Ighalo looked relaxed as he arrived at Carrington training on Friday as he looks to get back to match fitness after lockdown.
Shanghai are said to be open to allowing the 30-year-old to extend his stay at the club he supported as a boy - if he puts pen to paper on a two-year contract extension with them first.
He is currently tied down at Hongkou Stadium until December 2022 but has been offered a £400,000-a-week deal to stay in the Chinese Super League.