Speaking during the Red Devils' tour of the United States, Mourinho confirmed that the injury picked up by Antonio Valencia early on in the goalless draw with San Jose Earthquakes will likely rule him out of next month's league opener against Leicester City.
Summer signing Diogo Dalot is carrying an injury from his time at Porto, meanwhile, with his return date set for September, and the versatile Ashley Young has yet to return to training after playing a part in England's run to the World Cup semi-finals.
Lindelof, a centre-back by trade, may therefore be shifted out to the flank when Leicester visit Old Trafford on August 10.
"Antonio Valencia is injured, and I think he will be injured for the beginning of Premier League season. Diogo Dalot is also in a recovering phase, and he will not be ready for beginning of Premier League," Mourinho told reporters.
"Ashley Young is a possibility to play right-back, but he is on holiday, and I don't know if he fancies to be back for that and put himself up to be available for the team or stay on holiday.
"Victor Lindelof is a possibility there, he's not a right-back but he's a possibility, and he starts training next Monday. I will send people to Manchester to train with Victor, because it makes no sense for him to come to the US when we are leaving next week."