That is the view of BT Sport pundit and former Arsenal and England centre-back Martin Keown.
Huddersfield produced the shock result of the Premier League season so far, winning 2-1 at the John Smith’s Stadium.
Mourinho left Marcus Rashford and Henrikh Mkhitaryan out of the Manchester United starting XI for the match, opting for Jesse Lingard and Anthony Martial instead.
Keown says those selection decisions went a long way to costing the Red Devils the points.
“Jose Mourinho, I can’t help thinking leaving Rashford on the bench and Mkhitaryan, he’s got really what he deserves,” he said.
“He’s taken away some of the freedom from this team, put the handbrake on them.
“It’s not a tap you can turn on and off and they couldn’t respond today with enough to beat a Huddersfield team.
“That is a little bit of an embarrassment for Manchester United.”
Huddersfield are up to 11th in the table with 12 points from nine games and Keown admits they have surprised him this season.
“It is remarkable, they’ve already got more points than I thought they’d get for the whole season,” Keown added.
“To beat Manchester United today, what does that do for your confidence? (David) Wagner will feel now his players are Premier League players proper.
“When you come up there is that suspicion in the back of your mind, ‘do I belong at this level?’.
“Well now they surely do and that is a brilliant result for them tonight.”
United are now five points behind Manchester City at the top of the table.