Spanish top seed was too strong for Germany's Marterer and will take on Argentine Schwartzman in the last-eight
Nadal celebrates birthday by claiming 900th win and reaching French Open quarter-finals
Rafael Nadal delivered himself the perfect belated birthday present on Monday by reaching the quarter-finals of the French Open as the Spaniard insisted he does not "feel old".
Nadal, who turned 32 on Sunday, closed out a 6-3, 6-3, 7-6 win over a game Maximilian Marterer in the fourth round and will face Argentine 11th seed Diego Schwartzman for a place in the semi-finals.The world No 1's victory over Germany's Marterer was also his 900th win at ATP Tour level.
It also saw the Spaniard equal the record of 12 last-eight appearances at Roland Garros, which was set by Serbia's Novak Djokovic the day before.
Top seed Nadal is now on his own in third on the all-time list for most match wins at grand slam events with 234 victories after passing Jimmy Connors.
"I don't feel old, but I am 32, and I have been here since 2003, so it's a long way, a lot of years," he said. "I started very young. That's a real thing. But no, I feel happy to be here. Being honest, I am enjoying the day by day on the tour and I hope to keep doing this for a while."
Nadal powered 39 winners past Marterer, who pushed the Spaniard as hard as he could without ever threatening an upset.
Quarter-final opponent Schwartzman staged a thrilling comeback to down sixth seed Kevin Anderson 1-6, 2-6, 7-5, 7-6, 6-2.
"It's always good to see him in the quarter-final because he's a good friend, a good person. He's a worker, and I'm happy to see him having all this success," said Nadal, who had a brief practice session with Schwartzman last week.
The 16-time grand slam champion has now won 37 consecutive sets at Roland Garros, just four short of Bjorn Borg's record set between 1979 and 1981.
If Nadal's win was somewhat routine, Schwartzman had to fight back from the brink to set up his clash with the Spaniard.
Schwartzman clawed his way back from two sets down to stun Anderson and reach the quarter-finals for the first time.
He was totally outplayed in the first two sets, but twice broke Anderson when the South African was serving for the match to pull off a dramatic win.
The 25-year-old, who stands at 5ft 7in, said that the story of David and Goliath helped him believe he could down the 6ft 8in Anderson.
"Did you read David and Goliath? That's why. That's why," Schwartzman said. "I read it when I was young in the school, and I just try to think that when I see Kevin or the guys who have two metres."
World No 7 Anderson, who was looking to become the first South African man to make the last eight in Paris since Cliff Drysdale 51 years ago, has now lost in the fourth round at Roland Garros on four occasions.
Fifth seed Juan Martin Del Potro brushed aside John Isner 6-4, 6-4, 6-4 to reach the quarter-finals for the first time since 2012.
The 29-year-old Argentine was knocked out in the third round at Roland Garros last year after missing the previous four tournaments in Paris through injury.
Del Potro will next face either fellow former US Open champion and third seed Marin Cilic, who held off a fight back from Italy's Fabio Fognini to book his meeting with the Argentine.
Cilic, the 2014 US Open champion, appeared in cruise control when he took a two-set lead over a physically struggling Fognini, who called the trainer and was seen taking tablets.
However, the 18th seed claimed the third and fourth sets to force a decider before Cilic closed out the match 6-4, 6-1, 3-6, 6-7, 6-4.