Fulham have made a bid of €10 million for Pereira, who is on loan at Brazilian side Flamengo. Sources have told ESPN that United have given Fulham manager Marco Silva permission to speak to Pereira and that the 26-year-old has been impressed with the plans that were laid out.
Erik ten Hag has told Pereira he would like to assess him during the preseason tour of Thailand and Australia but the Brazil international is keen for regular first-team football and will have to decide whether he is more likely to get it at Fulham.
Fenerbahce have also registered an interest but are yet to make a formal offer.
Meanwhile, United are set to let Henderson join Forest on loan for the season. The 25-year-old goalkeeper struggled for opportunities at Old Trafford last season and is keen for regular football in the Premier League in a bid to force his way back into the England squad ahead of the World Cup in Qatar.
Sources have told ESPN that United expect more outgoings before the transfer deadline. The club are willing to listen to offers for Eric Bailly, Axel Tuanzebe, Aaron Wan-Bissaka, Alex Telles and Anthony Martial although they have not received anything concrete at this stage.
The first group of first team players are expected back to begin preseason training at Carrington on Monday.
Squad members who were not involved in the June Nations League games are set to work with Ten Hag for the first time since the Dutchman took over from interim boss Ralf Rangnick.
United's players will have two weeks of training at their Carrington base before departing for Thailand on July 8. Ten Hag will take charge of his first game against Liverpool in Bangkok on July 12 before travelling to Australia for the second leg of the tour.