He said: "Frank is sometimes a victim of his own high standards. He seemed to get a lot of criticism four years ago just because he didn't score but I remember him playing well. He was passing the ball well, it was just unlucky that he didn't score.
"In this tournament he's got nothing to prove. He's the best in the world at what he does and we're happy that we have him in the side.
"He is always good in training and is scoring lots of goals. Frank is one of the best trainers around. You know if he's in your team you have a chance. You don't play as consistently well as he does without training well."