Meanwhile, Andy Murray – who breezed past Viktor Troicki on Tuesday – learned the identity of his third round opponent as Frenchman Julien Benneteau beat Jurgen Melzer of Austria 6-4, 6-3.
Djokovic opened with a 6-1, 6-4 win against Andreas Seppi of Italy and his archrival Nadal followed up by beating Jarkko Nieminen of Finland 6-4, 6-3.
“I thought I was really focused first set. I had a tough opponent, obviously, a quality opponent that plays good on clay,” Djokovic said. “For the first match [on clay] since Roland Garros last year, it was satisfying.”
Nadal looked a bit rusty at times after not playing a match for three weeks to rest and treat his troublesome left knee.
“I played a really normal match, nothing special. Nothing very bad, but nothing very good,” said Nadal, who improved his overall record here to 40-1, including 38 straight wins. “First match on clay after long time without touching a racket.”
He broke Nieminen’s serve four times, and had the match closed for him when the Finn double-faulted.
The Spaniard, who has not won a title since last year’s French Open and has lost seven straight tournament finals to Djokovic, next plays Kazakhstan’s Mikhail Kukushkin.
Nadal’s last match was against Jo-Wilfried Tsonga in the Sony Ericsson Open quarter-finals. He pulled out of his semi-final against Murray to get treatment for a knee tendon problem, having skipped a chunk of the season to rest his knees following the Australian Open.
“I need practice, and today was a good practice,” Nadal said. “Tomorrow is going to be another tough match against a player who is dangerous.”
Nieminen’s heavy forehand pushed Nadal well back at times, and the Spaniard was broken for the first time when serving for the match at 5-2.
Djokovic’s match went more smoothly as he raced into a 4-0 lead after 19 minutes before Seppi started to fight back. Djokovic ultimately improved to 7-0 against the Italian.
The Australian Open champion next faces Alexandr Dolgopolov of Ukraine, who had 11 aces in his 6-2, 5-7, 6-1 win against Australian Bernard Tomic.
“You expect the unexpected with [Dolgopolov],” Djokovic said. “He’s a very talented player, comes up with some shots that are not really typical for a tennis player. He comes up with some drop shots, changes the pace very much.”
Although the 23-year-old Dolgopolov lost in straight sets to Djokovic in the fourth round of last year’s US Open, the Serb had to work hard to take a tight first set in a tiebreaker that finished 16-14.
“After that, I think I can compete with him,” Dolgopolov said. “I mean, he’s No 1, I’m No 21. Obviously he’s higher in the ranking. He’s playing more consistent. But I think I have my chances.”
Djokovic looked on course for an even easier win after the early double break put him in total control. But in a long fifth game lasting 11 minutes, the Serb was finally tested as Seppi showed some form with a couple of big forehands and one lovely drop shot. Djokovic even had to save two break points at 15-40.
“I think I served really well when I needed to,” Djokovic said. “That’s encouraging for the clay because you can’t rely on your serves as much as maybe other surfaces, so it’s good to have a couple of free points there.”
Elsewhere, there was an upset as Brazilian Thomaz Bellucci thrashed fifth-seeded David Ferrer of Spain 6-3, 6-2.
Sixth-seeded Tomas Berdych of the Czech Republic, No 7 Janko Tipsarevic of Serbia, No 8 Nicolas Almagro of Spain, and No 12 Kei Nishikori of Japan also won in straight sets.
Berdych beat Marin Cilic of Croatia 7-6 (3), 6-1; Tipsarevic won 6-2, 6-3 against Spain’s Albert Montanes; Almagro downed Italy’s Potito Starace 7-6 (3), 6-1, and Nishikori beat Frenchman Paul-Henri Mathieu 6-4, 6-2.
Kukushkin won 7-6 (8), 2-6, 6-2 against Filippo Volandri, while Switzerland’s Stanislas Wawrinka beat Spain’s Pablo Andujar 7-5, 6-3. Gilles Simon of France beat Portugal’s Frederico Gil 6-3, 6-0 and next plays Tipsarevic.