Leipzig are not a tough opponent for Manchester City. A relatively weak team is Leipzig. But there is no way to ignore this team. Smaller teams often win against bigger teams in the Champions League. Last season we saw Villarreal's great performances. And so if Manchester City want to qualify for the next round then they must play well. If they don't play well or make any tactical mistakes, they won't be able to win against Leipzig.
I think that Leipzig beat Real Madrid but that does not mean anything as Real was already qualified,in the games where Leipzig needed to win they have not been that good and convincing as a team.I believe Manchester City is going to have a very easy game against them and the qualification I believe to be a sure thing,I am not underestimating Leipzig,only judging objectively and by doing so Manchester City has a super squad compared to Leipzig in quality so it is only normal for them to qualify and yes I think they can afford some tactical mistakes during this game,the difference in quality permits that.