Liverpool boss Jurgen Klopp says the Anfield club would not be allowed to play like Manchester United after their goalless draw at Anfield on Saturday.
They peppered United, who enjoyed just 38% of possession, with 20 shots, but could not find a way past the brilliant David de Gea, who denied Joel Matip with a magnificent reflex save from close range.
Liverpool dominated for long spells but could not break United down, and Klopp said, according to ESPN: "I'm sure if we played like this, you could not do this at Liverpool. Obviously for United it is OK."
The Merseyside club have now won just once in eight matches in all competitions and have drawn the last three games as they struggle to repeat their goalscoring feats of last season.
In contrast, United have been finding the net more freely this season compared to last, with Romelu Lukaku to the fore - but the Belgium striker was a peripheral figure up front and the visitors' gameplan was built on containment.
As per the BBC, Klopp believes his side was unlucky not to beat their fierce rivals in what was another much hyped but ultimately low-key game between two of the most successful clubs in English football.
"It's quite difficult when a top-class team like United has that defensive approach," said the German.
"I think United came here for the point and they got it. We wanted three points and didn't get it. We were dominant, it is a home game for us so we should be dominant. I am okay with the performance - it is not my job to judge the United performance."
Mourinho described the second half as a game of chess and defended Manchester United's tactics when asked about his side's modest attacking ambition. The United boss, who did not start England striker Marcus Rashford as a result of a knock, said United came with the aim of three points.
"I was waiting for Jurgen to change, I was waiting for him to go more attacking but he kept the three strong midfielders all the time where he was having control because I only had Ander Herrera and Nemanja Matic," said Mourinho.
"When I brought on Jesse Lingard and Rashford I was waiting for him to bring on Daniel Sturridge or Dominic Solanke. But he decided to change player by player and kept the strong midfield. That midfield today was stronger than my midfielder."