Zlatan knew Ramos's tactic. Wrapping his hand against the opponent, and then forcefully pushing down, akin to a martial art throw. Zlatan was one step ahead. He kept his hand closer, and push Ramos first.
If Ramos wanted to tackle Zlatan then no one could have stopped him from doing that , his focus was on ball that's why he he didn't do anything there and also it was inside the box so if he would have tackled Zlatan then it would have been a penalty
my answer is true. zlatan caught Sergio Ramos from behind, it's like, if anyone caught someone from behind (in club football) they would definitely fall, so to know a true answer, it would be for them to hit each other head on, and not catch the person from behind like Ibrahimovic did.