Luis Enrique's men already find themselves trailing their arch-rivals by six points ahead of Saturday's encounter, having endured a stop-start beginning to their campaign.
A loss would see the Spanish champions trail Zinedine Zidane's side by a huge margin, making the quest for a third consecutive league win an uphill task.
The Spaniard, who is in Delhi to watch a screening of El Clasico organised by La Liga, told Goal: "It is probably the most important game in the world. Everybody is watching it.
"For both teams and their fans as well, this game is very important. Real Madrid currently sit six points ahead of Barcelona. Barcelona need to win tomorrow at all costs. So it will be a very exciting game for the fans as well.
"Luis Enrique has nothing to prove anymore. He has won so many trophies. Even when people started doubting him, he was always very clear. I know him very well as he was my team-mate in my first year in Barcelona.
"I know how he works so hard every day to become better and analyses every situation. So he has nothing to prove."
Garcia also took time to laud Zidane, who followed up a Champions League victory in his first season in charge at Madrid to lead his side to the La Liga summit this term.
"Zidane is also a very good manager," he continued.
"He took charge of the team in a very difficult spot last year. He took them to the final of the Champions League and they won it.
"Now they’re top of the table in Spain and looking strong in the Champions League. People didn’t expect that he would turn out to be such a good manager.
"But he was a great player in his playing days and now is proving to be a very good coach."