Whether Cristiano Ronaldo’s opener should have been ruled out or not boils down to one detail

Interference, that's the key word here.

No, we're not talking about what happened to your TV once a bird flew into the aeriel (anyone born in the 21st century can ask their parents what that means). We are, of course, talking about the offside rule in the context of Cristiano Ronaldo's opener against Atletico Madrid in the Champions League semi-final on Tuesday night. When the ball flew into the net, a lot of people were calling for the goal to be ruled out for offside. Didi Hamann was adamant that the linesman should have flagged. In his eyes, there wasn't a shadow of a doubt. https://twitter.com/DietmarHamann/status/859482037585162245 Let's take a look, shall we? Sergio Ramos floated in the first cross from the edge of the box, with Ronaldo in an offside position. However, Stefan Savic was able to get his dome to the ball and clear it. It only traveled as far as Casemiro though, who whipped in another that went straight to Ronaldo, who made no mistake with the finish. Obviously, it was the initial cross, not the actual assist, that caused the debate. Without a shadow of a doubt, Ronaldo was in an offside position, but should the referee have awarded a free out for offside? Since he didn't touch the ball, or blocked the goalkeeper's vision of the ball, the only grey area is whether Ronaldo interfered with an opponent or not - specifically, the defender who was standing behind him The official Fifa Rulebook states that interfering with an opponent:

"means preventing an opponent from playing or being able to play the ball by clearly obstructing the opponent's line of vision or movement, or by a gesture or movement which in the opinion of the referee deceives or distracts an opponent. The opponent must be reasonably close to the play so that the blocking, deceiving or distracting makes a difference."

Was Ronaldo's little jump enough to deceive or distract the opponent behind him? Was that defender "reasonably close to the play? The fact that no Atletico player raised their hand in protest leads us to believe that he was onside, but we'll let you argue it out amongst yourselves.