The Brazilian has scored six goals so far in the tournament and beguiled opposition defenders with his movement, strength and dazzling tight control.
It seems almost inevitable that chances will come Ronaldo's way on Sunday.
But if Kahn can continue his sensational impervious form and pull off a string of fine saves, his team will remain in the contest.
It could be the key battle of the final.
Dietmar Hamann v Ronaldinho
If Oliver Kahn has been the star of Germany's World Cup campaign then Dietmar Hamann has been his team's unsung hero.
He has provided excellent protection for his defence, breaking up opposition attacks in their infancy and winning alot of possession inside his own half.
Hamann may not catch the eye with mazy runs but when his team have been defending slender leads close to full-time is it usually Hamann who foils the other team.