Jose Mourinho fears Manchester United will be forced to play their Premier League derby trip to Manchester City in a dramatic end-of-season clash at the Etihad Stadium if they progress to next month's EFL Cup final.
United, who take a 2-0 first-leg EFL Cup semifinal lead to Hull City on Thursday, are currently due to visit their neighbours on Feb. 26 -- the date of the EFL Cup final at Wembley.
With United the only club currently competing in four competitions, progression to the latter stages of the FA Cup and Europa League would dramatically reduce options for a new date for the encounter with Pep Guardiola's team.
And with his team already facing trips to Arsenal and Tottenham Hotspur in the final weeks of the campaign, Mourinho admits he is bracing himself for an "amazingly difficult" late-season date at the Etihad Stadium.
When asked if United could challenge for all four trophies, Mourinho said, "I don't know, but I know it is going to be hard, if we go step-by-step, it is going to be hard.
"If we go to the fields of the 'ifs,' if we go to the EFL final and don't play Man City, I am sure they will choose an amazingly difficult moment for us to make us play that game.
"Then we have the Europa League, which is non-stop. The Champions League have a last 16, but we have a last 32 and a last 16, so if we progress, it will be really difficult."
United played a total of 63 games in all competitions on the way to winning the Treble in 1999, but Mourinho's team would face a minimum of 66 games if they progressed to the finals of the EFL Cup, FA Cup and Europa League.
And the United manager reveals he has already started to plan for the nightmare scenario of a fixture backlog.
"We go competition by competition, if we lose we go out, if we draw in the FA Cup, we have another match," he said. "It will be difficult.
"I have a board on my wall with all the possible matches and the image is quite difficult.
"Some teams have a wonderful life, they play at the weekend, have two days off and everyone rests.
"Then they have three to five days to play next match, with ideas clear, clear tactical work, every detail and that is a big difference.
"So let's see what happens."