Second seed Nadal completed the 6-2 6-2 victory in his first appearance at the tournament in Mexico since he claimed the title in 2005.
That year he went on to become the first man since Mats Wilander to win the French Open at the first attempt.
Fast forward eight years - and an era of utter domination on clay courts - and Nadal is seeking to rediscover his world -beating form after a seven-month lay-off with a knee injury which has seen him slip to fifth in the world.
The Spaniard said before the match against Schwartzman that he is still not 100 per cent happy with the condition of his knee, but he nevertheless eased past the Argentine qualifier with a minimum of fuss.
The 26-year-old is gunning for a second title from the three clay-court events he has played over the past four weeks. He reached the final in Vina del Mar in the first leg of his Latin American tour before winning the Brazil Open title in Sao Paulo.
Earlier, top seed David Ferrer - the man who has supplanted Nadal as Spain's number one men's player - wasted no time in seeing off the challenge of Antonio Veic, the world number four completing a straightforward 6-0 6-3 win.
Ferrer, fresh from retaining his Buenos Aires Open title at the weekend, is defending his crown on the red dirt in Mexico.
Meanwhile, another Spaniard Nicolas Almagro chalked up his 300th career win with a 6-0 6-1 dismissal of Mexican wild card Cesar Ramirez.
"I'm happy for the number and I hope there will be many more [wins] to come," third seed Almagro said. "I want to enjoy the moment a little but I need to keep working hard."
The world number 12 is the 20th active player to reach the milestone. Roger Federer has 886 wins to his name.
Acapulco International results
Aljaz Bedene (Slovenia) beat David Nalbandian (Argentina) 4-6 6-0 6-4
2-Rafa Nadal (Spain) beat Diego Schwartzman (Argentina) 6-2 6-2
Andrey Kuznetsov (Russia) beat 6-Thomaz Bellucci (Brazil) 4-6 6-4 6-4
8-Horacio Zeballos (Argentina) beat Simone Bolelli (Italy) 7-5 6-1
Fabio Fognini (Italy) beat 4-Stanislas Wawrinka (Switzerland) 6-2 7-6(3)
1-David Ferrer (Spain) beat Antonio Veic (Croatia) 6-0 6-3
Paolo Lorenzi (Italy) beat 7-Benoit Paire (France) 4-6 6-3 6-4
Tommy Robredo (Spain) beat Filippo Volandri (Italy) 6-2 2-6 6-4
Wayne Odesnik (U.S.) beat Lukasz Kubot (Poland) 6-3 6-4
Daniel Gimeno-Traver (Spain) beat Carlos Berlocq (Argentina) 6-3 6-3
3-Nicolas Almagro (Spain) beat Cesar Ramirez (Mexico) 6-0 6-1