"He is a player of Real Madrid, he is important for us and he is one of the best players in the world".
But after a close-season in which both managers have invested heavily in new players, United are now Mourinho's team and City have been created by Guardiola.
And whilst Willian admits a reunion with Mourinho was a possibility, he insists his sights are now set firmly on achieving more success with the Premier League champions.
Mourinho's side begin their Premier League campaign at home to West Ham on Sunday having enjoyed a strong pre-season, winning six out of seven friendlies before losing to Real Madrid in the UEFA Super Cup on Tuesday.
Ibrahimovic scored 17 Premier League goalslast season.
"I will just go with everything I have to try to win every match we play".
Mourinho has won the domestic league title at the end of his second year in each of his five major management jobs.
Mourinho's latest acquisition Nemanja Matic is perhaps the smartest piece of transfer from the Red Devils thus far, as the former Chelsea man provides the wall in midfield United lacked last season.
The Portuguese coach concedes his squad is "similar" to the one he took charge of last season.
Brighton and Hove Albion - Although in my bottom three, I see this as a great opportunity for Socceroos goalkeeper Mat Ryan as he's going to be very busy.
"I am not a hard person to work with and I understand the reality of the market, I understand the reality of the numbers - and I also understand that my club by doing 75 per cent of what I initially asked, I think the club did very well".
"I have conditions to deliver a better team than I did in the first season. But that spurs us even more, everybody writing us off already, so I hope we can prove them wrong".
"I did it, and now I need to look forward and think about this season in the Premier League". If pre-season is anything to go by Anthony Martial and Henrikh Mkhitaryan are full of confidence and if that transpires into the regular season opposition teams will have every right to be anxious. He believes he can do it again with United, but he accepts that the squad is "similar" to the one that fell 24 points short of champions Chelsealast season.