Cristiano Ronaldo is on a mission this World Cup.The Real Madrid forward has won almost everything in his career, but the world's biggest prize continues to allude him.Now 33 years old, Ronaldo knows that this summer's tournament in Russia is most likely the last chance he is going to get to achieve glory with his nation.And he is clearly doing everything in his power to ensure Portugal emerge victorious.Ronaldo was sensational in his side's opening game against Spain as he scored a hat-trick to salvage a 3-3 draw.And he was the hero again for his nation on Wednesday, scoring the only goal of the game to ensure his side triumphed over Morocco.But the debate still rages on. Who is the greatest in the world - Lionel Messi or Ronaldo?Some think that Ronaldo's early tournament form is a sign that he is the greater of the two.That is an argument that has been backed by Richard Keys, with the former Sky Sports presenter adding to the debate shortly after Ronaldo's headed goal v Morocco.Keys tweeted: "I think Ronaldo is ending the debate as to who is the world’s greatest player. Sensational again - with more to come."

That was always going to provoke quite a reaction, Richard.

There's no doubting that Ronaldo has been the player of the tournament so far.

He has already scored four goals and carried his side to four points.

That is in stark contrast to Messi, who struggled in Argentina's opening group game against Iceland, which ended in a 1-1 draw.

But can he really be saying Ronaldo has 'ended the debate' after just two group games?

It seems a little premature given how much can still happen this tournament.

And that was a view argued by many that responded to his tweet.

Do you think Ronaldo is 'ending the debate' for best in the world? Have your say by leaving a comment below.