A Xherdan Shaqiri double inside the final 17 minutes saw Liverpool return to the top of the Premier League table by defeating bitter rivals United 3-1 at Anfield on Sunday.
Alisson's first-half howler gifted Jesse Lingard and United an unlikely equaliser after Sadio Mane had put Liverpool ahead, but the tenacious Reds were not to be denied their first league victory over United since 2014 thanks to substitute Shaqiri.
Liverpool moved 19 points clear of sixth-placed United and Mourinho confessed his embattled team had no answer for the Reds' pace and aggression on Merseyside – singling out left-back Robertson.
"The players gave everything, and when the players give everything I am never frustrated towards them," Mourinho said during his post-match news conference. "I have a good feeling towards them. They play in relation to their qualities, the same way Liverpool play in relation to their qualities.
"They are fast, they are intense, they are aggressive, they are physical, they are objective. They play 200 miles per hour with and without the ball. I am still tired just looking at Robertson! He makes 100 metre sprints per minute, absolutely incredible, and these are qualities.
"When the game was really intense in the first 20-25 minutes, it was difficult for us to cope with it. In the second half when the game slowed down, when we were more compact and had more time to have the ball and play, we were in a good position in the game; 1-1 with 25 minutes to go and with some semi-dangerous approaches in the box.
"It's hard to lose in the moment where the game was dying, and when [Virgil] Van Dijk, Fabinho, [Dejan] Lovren, they were coming with the ball and couldn't find space, they had to shoot from 30 metres. Shots, easy for David [de Gea], shots in the stands, and it is in exactly that moment, when we were completely in control, that we lose the game. Two shots that David saves, easy shots, but because of the bounce, they were goals.
"I would say that Liverpool deserved the victory, but it's hard for my players to work hard like they did, and to lose in exactly the moment when we didn't believe we would lose.
"If you tell me in the first 25 minutes we are going to lose, I would say yes it looks so. But the moment we lost the game was the moment we didn't believe we would lose."