Ole Gunnar Solskjaer slammed referee Kevin Friend's "joke" decision to send off Nemanja Matic but was impressed with Manchester United's display in Wednesday's EFL Cup win at Manchester City.
Matic scored the only goal of the game in the first half, though the 1-0 victory for United was insufficient to book their passage through to the final, with City's 3-1 first-leg win ultimately proving decisive.
With United chasing a second goal towards the end, Matic was shown a second yellow card for a cynical trip on Ilkay Gundogan, adding to the earlier booking he received for catching Riyad Mahrez.
Solskjaer fumed at the dismissal and questioned why referee Friend was so harsh on Matic yet seemingly allowed several City players to escape punishment for infringements, with Pep Guardiola's men regularly criticised before for an apparent reliance on so-called tactical fouls.
"Of course, it's hard to come here [to the Etihad Stadium] and score a goal with 11 [men] never mind 10 [men], and it was never a sending off," Solskjaer told Sky Sports.
"It was an absolute joke, for me. It was ironic really that he gets a yellow on his first foul, almost gets a yellow on his second foul - which wasn't even a foul - and then the last one wasn't a yellow.
"How many times did they foul us? How many times was Daniel James fouled? How many times in the first half did they foul Jesse [Lingard]?
"That's the first question asked, and it shouldn't be like this because I'm so proud of these players.
"They've beaten City now twice in six weeks, at their place. We've come so far with these boys, they've given absolutely everything."
Despite the second-leg defeat, City will face Aston Villa in the final on March 1.