Jose Mourinho said he did not know why he was sent off in the final minutes of Manchester United's 1-0 victory at Southampton and blamed their underwhelming performance on the good weather.
Midway through the first half and 1-0 ahead through Romelu Lukaku's close-range finish, United appeared in such control that their latest convincing, one-sided win appeared almost certain to follow.
The hosts instead grew in confidence at the same rate at which United's energy waned, in the warm conditions, and to the extent that had their long-term struggles in the final third not continued, Mourinho's team would likely have dropped points.
They instead have a club record-equalling 16 for this stage of a Premier League season, though further difficulties could yet arise following Mourinho's dismissal by referee Craig Pawson in second-half stoppage time.
Asked why he had been sent off, Mourinho said: "I don't know. Craig told me to leave, and I left.
"Did I ask for an explanation? No. He told me to leave, and I left.
"[I collided] with the fourth official [Mike Jones].
"[My players] were really tired at the end. Nine of them didn't play in midweek [in the 4-1 defeat of Burton] so nine of them, it's not even an accumulation of fatigue.
"The weather was beautiful. Even if you train at 11 a.m., 12 p.m., 3 p.m. in Manchester, we don't get this weather. Seriously. The last time we had this was in Los Angeles and then in Macedonia, and they felt [it].
"I saw some players not sharp. Great spirit and always trying, but not the same sharpness. So if your opponent is coming with everything against you, let's do it for 10 or 15 minutes and stay solid.
"We are better this season than last. But this is nothing. It's just a start. I really think that six teams are going to fight for the title."
Mauricio Pellegrino's Southampton failed to score for the fifth time in seven fixtures since his summer appointment as manager and he said: "You have to score goals.
"I don't like to talk about good luck or bad luck, because we have to score goals and we couldn't.
"But, at the same time, we played a good game. In general we controlled the game against United, a team who are really difficult to control.
"To play in this way with this spirit, with this football, we'll win more games than we lose. I am sure. This is the best thing for us. We have to continue in this way."