Anthony Martial, Matteo Darmian and Daley Blind have returned to training at Manchester United amid doubts over their futures at Old Trafford.
Jose Mourinho and his coaching staff, including Michael Carrick, spent the day at Carrington on Tuesday before the players who have not been involved at the World Cup reported on Wednesday.
That group included Martial, Blind and Darmian, who have all been linked with moves this summer.
New signing Diogo Dalot was also at Carrington on Wednesday, along with Ander Herrera, Juan Mata, Alexis Sanchez, Luke Shaw, Chris Smalling, Eric Bailly, Antonio Valencia, Andreas Pereira, Timothy Fosu-Mensah and Joel Pereira.
Mourinho has around 17 senior players available for the tour of the United States, which will start with a flight to Los Angeles on Sunday.
He took a squad of 28 to the United States last summer, potentially leaving a number of places available for young players this time around.
Sources have told ESPN FC that Angel Gomes, Tahith Chong, James Garner, Ethan Hamilton, Mason Greenwood, Demetri Mitchell, Tyrell Warren, RoShaun Williams and Kieran O'Hara are among those being considered for the trip, which will consist of games against Club America, the San Jose Earthquakes, AC Milan, Liverpool and Real Madrid.