Defensive pair Chris Smalling and Marcos Rojo are training away from the rest of the Manchester United squad.
The Manchester Evening News says Smalling and Rojo are training in a separate bubble from the first-team squad at United's Carrington training complex.
The pair arrived at Carrington before 8am on Friday morning and both left before the rest of the first-team players turned up. Neither are expected to travel to Aston Villa for United's pre-season friendly on Saturday.
Smalling, 30, spent last season on loan at Roma and a permanent deal has partly been delayed by a change in ownership at the club following its sale to the US-based Friedkin Group, which was confirmed in mid-August.
Rojo, also 30, endured a chastening five-month loan with Estudiantes, where he played once following a mid-season move. His representative Jonathan Barnett admitted it was 'obvious' Rojo needed to leave United for good.
"I couldn't comment on what Solskjaer thinks but I think it's obvious," Jonathan Barnett said. "I think with Rojo, probably [a move] is more than likely somewhere else."