United were in talks to sign Alvaro Morata from Real Madrid, while Chelsea came agonisingly close to bringing Romelu Lukaku back to Stamford Bridge.
Morata and Lukaku ended up heading in opposite directions, though neither club will be disappointed with how things turned out.
Chelsea are currently nine points off the pace in the Premier League but that's through no fault of Morata, who's scored six league goals and assisted three in nine appearances thus far.
As for Lukaku, the Belgian is on seven for the season - albeit from one more appearance - and has recorded the same number of assists.
Despite ending up at Chelsea instead of United, Morata claims there are no hard feelings between him and his former manager, Jose Mourinho.
In fact, the pair are still in contact and regularly text each other.
"We speak, not only this summer," said Morata. "I have a good relationship with Jose. He was my first coach in professional football and he gave me the chance to be a professional.
"He made me the first contact. Sometimes we send messages, not speaking about football, asking if everything's OK and sending some jokes."
Morata claims Mourinho first made contract with him after his move to United collapsed in the summer - so why exactly did it fall through?
According to various sources, Morata was so excited about the idea of moving to Old Trafford that he dyed his hair red.
Well, according to the Spaniard himself, he was the one who rejected Mourinho and United when he received personal contact from a number of Chelsea figures.
"Antonio, Michael [Emenalo], Marina [Granovskaia], all of them called me this summer and there was no chance I wasn't coming to Chelsea," he revealed, per Goal.
"They demonstrated to me that they really wanted me. I had the chance to go to Manchester United and other teams in the Premier League.
"The important thing is I'm part of Chelsea and I'm very happy with this and now it's time to fight for the blue shirt. I want to play well and win with this shirt."
Morata has been phenomenal for Chelsea since joining for £58 million in July, but there are few bigger tests than United. Time to show Mourinho what he missed out on.