It may seem a strange thing for the United boss to have to say to a squad of highly-paid internationals, who are deemed good enough to be with one of the biggest clubs in the world.
But Mourinho revealed he had to deliver that message against Burnley at Old Trafford on Boxing Day, when they were trailing 2-0. His players responded in the second half to fight back to draw 2-2 and they had the chance to increase their momentum in only the fourth minute.
Juan Mata crossed from the right, but Lukaku headed over from a good position. Five minutes later, the United striker was knocked out when Saints defender Wesley Hoedt challenged him from behind in the air. Hoedt headed the back of Lukaku’s head and after four minutes of attention, Lukaku was carried off on a stretcher.
In between those incidents, United keeper De Gea had to make a smart save from James Ward-Prowse, who should have done better. And in a bright start by Southampton, De Gea made another save from a better effort by Ward-Prowse, this one from a free kick.