Any result is certainly possible, because Manchester City and Real Madrid will certainly do their best no matter what their previous results are, and no matter what their domestic league trends are like. But for now, I think because Real Madrid's squad is dominated by young players, it might be difficult for them to get good results. Although, with a young squad it will give better energy too, but if for example Ancelotti doesn't make the right strategy and tactics, then it is possible for Real Madrid to be eliminated. But yes, basically this match will certainly be a difficult match for both teams, because both teams are basically title candidates, so they have the same level too.
I don't think Madrid is going to allow Manchester City get an easy win that is if eventually they win but then we can expect any thing to happen as both teams are very much experienced in the Champions League, and they both have a very good squad who has got the capabilities to handle the game, except that PEP has had some personal issues in recent times which may affect his performance but lets hope it doesn't get the greater part of him in this game to the point he losses it easily.
His personal issue has already affected the club's performance because he is human and will have divided mind. The match is in two days' time, and we shall all know which of these two clubs will win the match. Madrid has a weak defense but not as porous as that of City, which means that the attackers are the ones to decide who wins the game. I will bet on Madrid because their attackers are very sharp and sound.