But they lost out to City after a 14-game winning streak to finish the season and De Bruyne says it shows they were better than Jurgen Klopp's side.
Asked whether Guardiola's Man City team was the best he's ever seen, Foster said: "When I was part of the Man United side that beat Chelsea in the Champions League final, that's probably the best team I've been involved with". But we're still competitors. But to win in the way they have done surely has to count for more, and even if that elusive UEFA Champions League title continues to evade them, they have to be considered one of the greatest teams in European history, let alone English history. Leo [Messi] missed a penalty [in Barca's 2012 semi-final against Chelsea], Muller missed a penalty [in Bayern's 2016 semi-final against Atletico Madrid], Sergio missed a penalty [in this season's first leg against Spurs]; these kind of little details in the domestic leagues you get another chance.
"They have to feel they must win again or they will have problems, they are in trouble and won't be here any longer". Having beaten Watford twice this season gives the club plenty to work with in order to repeat, but the magic of the FA Cup final produces surprises.
"We know what to expect from Man City and if one of their world class players produces a bit of magic then sometimes it's very hard to stop but we know we have players that can also produce a bit of magic and can score fantastic goals too". You're not going to extend his contract because you don't want him.
"He's been competing with [Raheem] Sterling and Bernardo Silva".
"On Saturday, the main thing for us to focus on is how we are going to play", Foster told Squawka.
He said: "Every player has to feel, "I have to play good or I don't play". "It is top. When he is fit he is incredible".
Sane has two seasons left on the deal he signed when he joined City for £37m from Schalke in 2016 but talks over an extension are yet to reach fruition.
Guardiola also said that he was concerned the footage had been leaked by somebody who had been on the flight, and added: "You know my opinion over social media".