The Red Devils boss Ole Gunnar Solskjaer expects to build on the £15m capture of Daniel James from Swansea by securing the deal.
Earlier this month, the midfielder promised to remain in Newcastle in an interview, the United are confident they can land the 21-year-old.
The uncertainty at Newcastle, with a proposed takeover imminent and the future of boss Rafa Benitez, is expected to work in Solskjaer’s present.
Longstaff, who made 11 successive starts for Rafa Benitez’s side last season, before he suffered knee ligaments against West Ham on March 2, which bring an end to his season.
Solskjaer had seen enough of the player, despite that setback, he convinced that the player is fit for the profile of the kind of player he wants at Old Trafford.
According to L’Equipe, Liverpool and other top European sides have been signified interest in the player who had a great showing in the La Liga last term.
Chukwueze, 20, cost Villarreal only €500,000 when he joined them a season and a half ago.
He has a contract with the Spanish club until 2023, but clubs who want to sign him before then will have to dole out €63million, the release clause on his contract.
The wing wizard bagged eight goals and also had three assists in 38 games in all competitions during 2018/2019 campaign.
The UK Mirror reports that the discussions are expected to take place over the summer, with Aubameyang out of contract in two years time.
The Gabon international is likely to receive a raise in pay after a season in which he shared the Premier League Golden Boot, after scoring 22 goals.
He is currently thought to be on around £190,000-a-week.
Reports have it that Guangzhou Evergrande and Shanghai SIPG have both made moves for the player and have offered an eye-watering £300,000-a-week, in order to try to tempt the 29-year-old to the Chinese Super League.
Meanwhile, the Gunners are also due for talks for Aubameyang’s strike partner Alexandre Lacazette.