Three of Manchester United's senior players are reportedly going to miss the start of the new season with injuries, according to Goal.com.
"They have no chance for the beginning of the Premier League season," claimed Mourinho.
All three of the injured players are with the United squad for their pre-season tour of the United States, in order to continue their rehabilitation with the club's medical staff.
22-year-old Shaw suffered ligament damage to his foot in the 1-1 draw against Swansea City in April, however is expected to to be the first of the trio back to full fitness.
Young injured his hamstring in United's Europa League semi-final with Celta Vigo and is expected to be the next of the trio to recover.
Rojo sustained a more serious injury during the previous round of the Europa League, against Anderlecht.
Nevertheless Mourinho said he has been pleased with the progress the trio have made so far:
"Luke Shaw is the first one to recover, Marcos will be last and Ash will be in between. Luke is September, Young is October and Rojo is December, or maybe January," claimed Mourinho
"The group is really strong and it's good to be together. It's important for them to be with us and not be in Manchester working at home."
Mourinho will also be concerned about Ander Herrera who hobbled of during United's pre-season win over Real Madrid yesterday.