Nadal committed 30 unforced errors to Schwartzman's 17 and had his serve broken five times.
The decision by the 36-year-old Swiss, who was stunned in the final of last year's Rogers Cup in Montreal by German Alexander Zverev, comes less than two weeks after his quarter-final loss at Wimbledon.
Top seed Novak Djokovic beat Canadian Felix Auger-Aliassime 7-5, 7-6(1) to reach the semi-finals of the Italian Open on Friday and move within one win of 1,000 career victories.
Nadal had a solid start, but the 35-year-old struggled physically towards the end of the contest
Images from Day 6 of the 2023 Australian Open at Melbourne Park on Saturday.
Muguruza wins all-Spanish clash with Badosa at WTA Finals
Nadal surpassed the haul of Roger Federer and Novak Djokovic.
British No 1 Cameron Norrie overcame a slow start to beat Frenchman Hugo Gaston 6-3, 7-5.
The list of players who have been defaulted from a tour-level match for on-field misconduct.
Earlier, Ukraine took a 2-0 lead over Japan as world number five Elina Svitolina took the first point of the Billie Jean King Cup era.
A summary of Wednesday's action at the US Open.
Thiem, Wawrinka stay positive after defeats on return
Organisers played a wrong national anthem for Moldova ahead of their tie against Belgium in Sydney. Denis Shapovalov won the battle of the next generation against Greek Stefanos Tsitsipas to help Canada to an emphatic 3-0 victory in the inaugural ATP Cup men's team event in Brisbane on Friday.
IMAGES from Day 3 of the 2022 French Open at Roland Garros in Paris on Tuesday.
India's No. 1 ranked player Saketh Myneni and Norway's tennis sensation Casper Ruud have been offered the last two wild cards for the 22nd edition of the Aircel Chennai Open.
A summary of Friday's action at the US Open.
Australia's Nick Kyrgios has branded Rafael Nadal a sore loser, the Spaniard's uncle Toni an "idiot" and said world number one Novak Djokovic has a "sick obsession" with being liked.
IMAGES from Day 1 of the Wimbledon Championships played on Monday.
Images from Day 2 of the French Open matches played at Roland Garros on Monday
Australian Nick Kyrgios was expelled from the tournament after going wild in the third set of his match against Casper Ruud.
The hosts had blanked Germany in their opening tie and became the first to seal a quarter-final spot with their second 3-0 win in the inaugural team event.
IMAGES from Day 6 of the French Open, at Roland Garros, on Friday.
'He can say what he wants, I don't have a problem with it. Does he show me the same amount of respect that most other players do? No, he doesn't, but that's the way he communicates these days'
The trick-shots, underarm serves and tirades at spectators are all part of the theatre, and the 'what will he do next?' lure puts bums on seats, in much the same way John Daly still draws a crowd in golf.
Images from Monday's action at the Australian Open.
World number one Rafael Nadal won a battle of attrition against fellow left-hander Yoshihito Nishioka of Japan 7-6(4), 6-4 to seal Spain's spot in the final eight of the inaugural ATP Cup in Perth on Wednesday. Meanwhile his long-time rival, world number two Novak Djokovic, had an easier outing in Brisbane, strolling past Chile's Cristian Garin 6-3, 6-3 to stay undefeated in the new year.
World number five Alexander Zverev continued his poor recent form as he crashed out of the Italian Open in the second round while Serena Williams had to pull out of the women's draw with a recurring knee injury.
Rafael Nadal left German qualifier Yannick Maden no hope as he booked his ticket for the third round of the French Open in ruthless fashion with a 6-1, 6-2, 6-4 victory.
A summary of sports events and persons who made news on Monday
A summary of sports events and persons who made news on Thursday