Manchester United manager Ole Gunnar Solskjaer expressed his frustration at the Football Association's scheduling after local rivals Manchester City were handed an extra day to recover ahead of Sunday's derby.
United eased past Derby County 3-0 in the FA Cup fifth round on Thursday, but City have had an extra day to prepare for their Premier League trip to Old Trafford after beating Sheffield Wednesday a day earlier.
"It's that help we get from the FA again, that extra 24 hours that they've [City] had. I cannot believe why there's a derby on Sunday and we've got to play Thursday night," Solskjaer said. "What's the point in that? That doesn't level the playing field."
City also had an extra day to prepare ahead of December's derby at the Etihad Stadium, although goals from Marcus Rashford and Anthony Martial secured a 2-1 win for United.
"It was the same when we beat them last time to be fair, we played Wednesday and they played Tuesday. Those 24 hours are important so we've got to be good at recovering now."
Asked if he had complained about the scheduling this time, the Norwegian said: "No, I've not. I don't think we can. It's one of those where you get told when you're going to play, so we've not got any help before this one."
United may have less rest but they go into the derby with some momentum, having set up an FA Cup quarter-final with Norwich and taken their unbeaten run to nine matches in all competitions.
That consistency has been lacking this season but Solskjaer has often got his side to rise to the big occasions, including December's Premier League win at the Etihad Stadium and a 1-0 triumph there the following month in the Carabao Cup semi-finals.
But that second leg victory was not enough to make up for the 3-1 loss inflicted by Pep Guardiola's men at Old Trafford, where a meek start proved their undoing – something Solskjaer knows cannot be repeated.
"When you're at home and you have to open up against a team like Man City, they will exploit that if you're not 100 per cent," he said.
"Sometimes being at home with your fans, you want to show them what you can do and beat your opponent, and sometimes you open too many spaces.
"That's what we did for those 10-15 minutes or 20 minutes after they scored a worldie. Before then, it wasn't a problem, before Bernardo [Silva] scored in the top corner.
"It wasn't an issue until our heads went for a little while, so we've got to control our emotions more. And we have, we have learned, so that's an experience we'll bring into this game definitely."
Meanwhile, Guardiola's City have won their last five matches, including a Wembley final against Aston Villa for their third straight League Cup title.
"They'll feel confident," Solskjaer said. "They've hit form, they're playing well. They've just been at the Bernabeu winning there [against Real Madrid], they've won the cup final so I'm sure they'll come confident."
United captain Harry Maguire was unavailable against Derby with an ankle injury, and now faces a race to be fit to face City in a crucial match for United's Champions League qualification hopes.
"Well, he's touch and go because he rolled his ankle but, hopefully, he'll recover quickly," Solskjaer said. "I wasn't going to rest him [against Derby], I didn't give him a day off birthday-wise but I hope he'll be fit."
Gallery: City retain League Cup
