Jose Mourinho faces his toughest test as Manchester United manager today when he welcomes Pep Guardiola and Manchester City to Old Trafford.
Ahead of the biggest derby game in years, and the biggest game of his young United reign, the Portuguese manager would have been hoping for a smooth run in to the fixture.
However, writing in his programme notes to fans at this afternoon's game, Mourinho has admitted that one issue over the past few days has left him frustrated.
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"It has been a strange week at the AON training complex," the Red Devils boss wrote, "because of the international break.
"Players have been arriving back with us day by day from all over the world, so of course it has been frustrating to be unable to work more with them and prepare them thoroughly for today's derby."
Here are his words in full...
The recent international break has long been scheduled in the football calendar, but that doesn't make it any easier to work around.
Only today we reported on how United had had to schedule a private jet to get Antonio Valencia back from Peru in time for a Thursday training session.
On Friday, too, Mourinho hinted at his frustration with the fact that, unlike the Manchester City internationals, Valencia and Marcus Rojo had been unable to get direct flights straight from their respective national team meet-ups back to Manchester.
Clearly, with such a big game taking place today, the former Chelsea and Real Madrid boss is far from pleased that his preparation has been disrupted by an inability to work with all of his first team squad all week.
However, the veteran manager did accept that this sort of predicament does come with the territory when you're the manager of Manchester United.
"This is a consequence of having such a good squad which has so many players of international standard," he continued.
With the eyes of the world watching, hopefully the disjointed preparation and potential jet lag won't affect the performances on the pitch today.
United fans will also be hoping that Mourinho has managed to put together a winning formula despite the comings and goings at the training ground this week.
Whether that plan includes Marcus Rashford - a hattrick hero on his England under 21 debut this week - remains to be seen.