Mason Greenwood and Donny van de Beek are set to be the first Manchester United players sold this summer.
United are in advanced talks with Marseille over Greenwood who was at Carrington to discuss his options on Monday but did not train with the rest of his teammates on the first day of pre-season.
Greenwood, who spent last season on loan at Getafe, is understood to be getting impatient over his situation, with a number of clubs - including Lazio, Juventus, Atletico Madrid and Valencia - also showing a strong interest in him.
However, Marseille appear to be favourites to win the race for his signature.
The French club are said to have tabled an offer worth £25million plus add-ons and a substantial sell-on fee, although the two clubs have also discussed a loan deal with an obligation to buy at the end of the season.
Mason Greenwood, pictured on loan at Getafe last season, is set to leave Manchester United
Dutch midfielder Donny van de Beek, 27, is also on his way out of Old Trafford this summer
Van de Beek is on the verge of ending a miserable Old Trafford career, with United close to finalising terms with Girona for the Dutch midfielder.
United are ready to accept a fee of £450,000 for a player who cost £35m from Ajax four years ago, although the deal would include add-ons up to £16m as well as a sell-on clause.
A number of other players could be on the move to fund new signings this summer, with Juventus leading the chase for £40m-rated Jadon Sancho, Fenerbahce interested in Victor Lindelof, and Galatasaray and West Ham tracking Aaron Wan-Bissaka.
Real Valladolid are said to be considering a move for Facundo Pellistri who spent the second half of last season on loan at Granada.
Casemiro reported for pre-season on Monday morning but United are still keen to get the Brazilian's £375,00-a-week salary off the wage bill by selling him to a Saudi Pro League club.
Casemiro reported to United's training ground on Monday but the club want to sell him
Juventus are hoping to sign Jadon Sancho, who spent half of last season on loan at Dortmund
Meanwhile, Scott McTominay could emerge as a target for Fulham and Everton.
United would be reluctant to sell McTominay, having turned down a £30m bid from West Ham last summer, but the Scotland midfielder is understood to want a regular place in the first-team.
Like Greenwood, McTominay would generate 100 per cent profit as United look to comply with profit and sustainability rules and raise money for new signings.
They want to bring in two centre-backs in Matthijs de Ligt and Jarrad Branthwaite if possible.
Bologna striker Joshua Zirkzee and Paris Saint-Germain midfielder Manuel Ugarte are also top targets.
Joshua Zirkzee, pictured playing for the Netherlands, is one of United's top transfer targets
Fellow Dutchman Matthijs de Ligt is another player who sits high in United's wanted list
United's first pre-season friendly of the summer is little more than a week away.
The Red Devils will take on Rosenborg in Norway on July 15 before heading to Scotland to face Rangers in Edinburgh.
A trip to the USA will then see United meet Arsenal, Real Betis and Liverpool, before a reunion with Manchester City in the Community Shield at Wembley on August 10.