Long linked with a return to Chelsea, it was United who swooped to sign him for an initial £75million and they hope he can fill the voids left by Zlatan Ibrahimovic and Rooney.
The City line-up for their 1-0 win was all-British but the eleven who will take the field on Saturday will be drawn from around the world - with even more worldwide talent having been recruited during the close-season.
United last won the title in 2012-13, but they collected three trophies last term under Jose Mourinho and have beefed up the spine of their team with big-money signings in the shape of Victor Lindelof, Nemanja Matic and Romelu Lukaku. Both Guardiola and Mourinho could argue that their first seasons were transitional campaigns.
City's Arab billionaire owner Sheikh Mansour has invested more than 200 million pounds in new players during the close-season adding to their already impressive attacking options and upgrading their identified "weak spots" at full-back and goalkeeper. But as Guardiola found out last season, often with a look of painful frustration, it's not as simple as that. With more playing time likely coming his way this season, his total should grow this year. There were new players that were bought and everybody had to get used to the methods of their high-profile bosses. All three are excellent players who can cope with the physical demands of Guardiola's system, though it's unclear whether they have the technical quality to step into central midfield like Philip Lahm and David Alaba did to such good effect at Bayern Munich. Sort out the defence, over which there are still question marks, and City will take some stopping.
Manchester City had something to cheer in the cup competitions under Pellegrini as well: they finished first in their UEFA Champions league (UCL) group and progressed to the semi-finals for the first time ever in their history.
The 18-year-old right back made his senior debut for Liverpool in October and has only started two Premier League games. Brazilian Gabriel Jesus who shone during his brief show last season, is now fit and raring to go.
Who's going to win the title? Since then everyone else have tried and failed. I think last season there was a movement away from how the team played under Louis van Gaal's side and I think it will become more of a Mourinho side.
The same newspaper says Liverpool is preparing itself to receive a fourth bid from Barcelona for star playmaker Philippe Coutinho, as the Spanish club looks to replace Neymar. If they can, they pose a formidable threat, again blessed with frightening pace.
Pep Guardiola's first year at Etihad Stadium was overwhelmingly disappointing and the Catalan coach is aware this is a make or break season for him. "Our biggest challenge is to be stronger defensively as a team".