Paul Pogba is likely to stay behind and work on his fitness, rather than travel down with the squad which faces Bournemouth on Sunday.
The £89m midfielder was ruled out against the Cherries after it emerged the former Juventus man must serve a one-match ban he picked up in Italy.
United fly down to the South Coast later on Saturday and Pogba was keen on making the journey anyway, but the world’s most expensive player is still a little short on his fitness, according to United’s conditioning team.
The France international has spent the last couple of days working alongside them and they want to continue in the same vein over the weekend.
It’s understood Mourinho is to make a late decision on the matter, but he will not want any outside distractions as his team attempt to kick-off the new campaign with a maximum haul.