When Jose Mourinho was drawing up a list of targets ahead of the summer transfer window, one thing he looked at was Champions League experience.
Nemanja Matic had it. So did Victor Lindelof. But Romelu Lukaku didn't and so Alvaro Morata, who did, was also considered.
In the end, Mourinho picked Lukaku, deciding it was easier to make the transition from Premier League to Champions League than La Liga to Premier League.
After all, the main objective this season, whether Mourinho will admit it publicly or not, is to win the title.
Still, that will be briefly forgotten this week when the Champions League returns to Old Trafford for the first time since November 2015.