Cristiano Ronaldo is only 27 years old. He has 139 goals in 138 games for Real Madrid. He has won the Premier League, Champions League, Copa Del Rey and Ballon d'Or. He is without question one of the greatest footballers to ever live. And he can't beat Barcelona.

He did it once, in last season's Copa Del Rey final. His headed goal in extra time beat Barcelona, and at that time, it seemed like he was going to get the monkey off his back. Instead, his struggles against Barcelona got worse in the Clasicos after that game. Things hit a low point during the first league meeting between the two teams this season.

Real Madrid took the lead 23 seconds into the first Clasico and would not score again. Just before the half hour mark, Ronaldo missed an absolute sitter that would have doubled Madrid's lead, and that was followed by an Alexis Sanchez equalizer less than 60 seconds later. Barcelona would go on to take a 2-1 lead, but Ronaldo had a chance in the equalizer in the 65th minute. Again, he missed a sitter. Again, less than 60 seconds later, Barcelona scored.

Football might be the world's ultimate team sport, in which one player cannot be the reason for a win or a loss, but Ronaldo came incredibly close to being solely at fault for Madrid's loss to Barcelona in December. It was arguably the low point of his career. He had a chance to put his team up 2-0, then a later chance to equalize when his team trailed 2-1, and he inexplicably failed to finish both of them. It was hardly the first time that Ronaldo seemed to simply forget how to score against Barcelona.

This game probably won't define the legacy of Cristiano Ronaldo, but eventually, a Clasico is going to define his legacy one way or another. Either he's going to put in a man of the match performance in a late league or Champions League Clasico or he's going to come up short in the final one he plays in.

It's unfair to judge a player -- especially one as incredible as Ronaldo -- by his performances against one team, but he knew what he was getting into. He knew when he came to form the second iteration of the Galacticos that he would be expected to lead Los Merengues to big victories against Barcelona, and it hasn't happened yet. He is continuously overshadowed by Lionel Messi, a man who he has outplayed this season outside of the Clasicos between the two teams.

Everyone is going to talk about this until Ronaldo outplays Messi to win La Liga or the Champions League. He has a chance to shut everyone up forever on Saturday.

We'll have pre-game and live game coverage in our Barcelona vs. Real Madrid, 2012 El Clasico StoryStream. For more on the two teams, head over to Real Madrid blog Managing Madrid and FC Barcelona blog Barca Blaugranes.