A win for Madrid would effectively end Barca's hopes of winning a fourth-straight La Liga. For this to happen, Ronaldo must make a statement to the world that he can dominate against top opponents in important matches.
Other than the Copa del Rey final last year, Ronaldo has had few shining moments against Barcelona while wearing a white Madrid shirt.
Ronaldo has played Barcelona five times in league play and has scored just one goal, which came from the penalty spot in last year's meeting at the Santiago Bernabeu. In those matches, Madrid came out 0-4-1.
The comparisons to Barcelona star Lionel Messi will never end for Ronaldo—even after both of them retire—so what Ronaldo needs to focus on is carrying his club to victory in a huge game.
Madrid can still win the Champions League but face a stiff test against Bayern Munich, who won the first leg on Wednesday 2-1 at the Allianz Arena.
Madrid is also out of the Copa del Rey, so the league title is their best chance at securing a trophy this season.
In the biggest matches, your best players must set the example and lead the club to victory. Ronaldo has been unable to do that against Barcelona throughout his career.
He must bring a ton of energy and passion to the pitch on Saturday, while using his speed and dribbling skills to cause problems for the Barca defense.
Ronaldo has to find a way to beat Carles Puyol, Dani Alves and Gerard Pique consistently or Madrid will have a challenging time earning all three points on Saturday.
Madrid need a signature win to give them confidence heading into the final weeks of the season—and Ronaldo must achieve this for them in El Clasico.