Nadal was in unstoppable form during periods of the match as he steamrolled to a 6-1, 6-3 win.
"You can work very hard on the practice courts, but when you get into matches it's completely different", Djokovic told reporters afterward.
The 31-year-old is to face another Spaniard, Guillermo Garcia Lopez, who progressed after Kei Nishikori retired.
Per the ATP, Nadal has five streaks of 30 or more clay sets won - the most recent before the current streak occurred during the 2012 season.
Nadal will face compatriot Guillermo Garcia-Lopez in the last 16.
"But obviously there's a guy named Rafael Nadal who is always on the way to winning more "big titles" and he still keeps on dominating this surface, and he's definitely always the guy to beat". "My motivation and my hope is to do my best and compete well every week, the rivals also want to win, not just play", Nadal said, as quoted by Daily Express.
Leeds owner defends Myanmar tour: 'This is about people not governments'
The Leeds United tour is being planned in partnership with AYA Bank, a Myanmar financial institution. The club now sits in 12th place in the Championship, England's second-tier league.
Earlier, second-seeded Grigor Dimitrov defeated Gilles Simon of France 6-2 6-1, while third-seeded Thiem beat qualifier Jaume Munar 7-6 (8) 6-1.
The Slovak impressively dismantled Novak Djokovic on Tuesday to book his spot in the third round and he now awaits Rafael Nadal, should the world No. 1 come through his tie later.
Djokovic chose to play in Barcelona after losing to Dominic Thiem in the third round of the Monte Carlo Masters. Nishikori had lost to Nadal in the Monte Carlo Masters final on Sunday and he pulled out after conceding the first set to Garcia-Lopez 6-3.
He missed last year's U.S. Open and the Australian Open at the start of 2018 after injuring the same wrist in August.