Paris - Juan Martin del Potro set up a potential French Open blockbuster against Andy Murray on Thursday after a heartfelt display of compassion towards a stricken rival.
The giant Argentine, no stranger to injury after a career-long battle with wrist problems, made the third round after Spanish opponent Nicolas Almagro quit in tears during the third set of their tie with a left knee injury.
In a moving conclusion on Court Two, Del Potro sat next to the stricken, sobbing Almagro, offering him water while patting the head of the inconsolable 31-year-old.
Del Potro had also gone to the Spaniard's aid when he had collapsed at the back of the court, weeping, just moments earlier.
Del Potro, 28, had taken the first set of the second round clash 6-3 before Almagro claimed the next by the same score.
They were locked at 1-1 in the third when Almagro quit.
Del Potro, playing Paris for the first time in five years after battling a series of wrist injuries, also suffered an injury scare himself when he pulled up, holding his left leg in the second set.
The former US Open champion goes on to face either world number one Murray or Martin Klizan for a place in the last 16.
Del Potro reached the quarter-finals on his last appearance in 2012 with a best run to the semi-finals three years earlier.
Murray, the 2016 runner-up to Novak Djokovic, tackles fiery Slovak Klizan for a place in the third round.
World number 50 Klizan has already hit the headlines in Paris by being accused of faking an injury in his opener against French wildcard Laurent Lokoli.
Third seed Stan Wawrinka, the 2015 champion, was bidding to make the last 32 for the 10th time against Alexandr Dolgopolov of Ukraine.
Japanese eighth seed Kei Nishikori routed France's Jeremy Chardy 6-3, 6-0, 7-6 (7/5).
The world number nine will face South Korean Hyeon Chung for a place in the last 16.
Nishikori's best performance at Roland Garros came in 2015 when he reached the quarter-finals.
Former US Open champion Marin Cilic, the seventh seed, made the third round for the seventh time thanks to a comfortable 6-3, 6-2, 6-2 win over 32-year-old Konstantin Kravchuk, the Russian world number 129 making his Paris debut.
"How far I can go? I don't know. It's not up to me only. I'm very satisfied with the way I'm playing," said Cilic.
Unseeded 21-year-old Karen Khachanov of Russia continued his impressive debut, beating Czech 13th seed Tomas Berdych, a semi-finalist seven years ago, 7-5, 6-4, 6-4.
Big-serving John Isner of the United States fired 21 aces to defeat Italy's Paolo Lorenzi 6-3, 7-6 (7/3), 7-6 (7/2).
Isner and Lorenzi were two of the 30 men in the second round aged over 30 -- an Open era record at any Slam.
Czech second seed Karolina Pliskova and third-seeded Simona Halep of Romania, both firm women's title favourites after the first round exit of world number one Angelique Kerber, look for places in the last 32.
Pliskova has never got beyond the second round in six previous attempts.
The 25-year-old Czech faces Russian world 86 Ekaterian Alexandrova who has never beaten a top five rival.
Halep, the 2014 runner-up, said she was "50-50" at the weekend due to an ankle ligament injury picked up in Rome.
But after her opening round win over Jana Cepelova she said she was "80 percent recovered".
On Thursday, she faces German world number 102 Tatjana Maria who is bidding to make the third round for the first time.
Fifth seed Elina Svitolina, a quarter-finalist in 2015 and recent Rome champion, made the third round by beating Bulgaria's Tsvetana Pironkova 3-6, 6-3, 6-2.
Poland's Agnieszka Radwanska, seeded nine, saw off Belgian qualifier Alison Van Uytvanck 6-7 (3/7), 6-2, 6-3.
French Open results on Thursday, the fifth day of the 2017 tournament at Roland Garros (x denotes seeding):
Juan Martn Del Potro (ARG x29) bt Nicolas Almagro (ESP) 6-3, 3-6, 1-1 -- retired
John Isner (USA x21) bt Paolo Lorenzi (ITA) 6-3, 7-6 (7/3), 7-6 (7/2)
Karen Khachanov (RUS) bt Tomas Berdych (CZE x13) 7-5, 6-4, 6-4
Kei Nishikori (JPN x8) bt Jrmy Chardy (FRA) 6-3, 6-0, 7-6 (7/5)
Feliciano Lopez (ESP) bt David Ferrer (ESP x30) 7-5, 3-6, 7-5, 4-6, 6-4
Marin Cilic (CRO x7) bt Konstantin Kravchuk (RUS) 6-3, 6-2, 6-2
Elina Svitolina (UKR x5) bt Tsvetana Pironkova (BUL) 3-6, 6-3, 6-2
Magda Linette (POL) bt Ana Konjuh (CRO x29) 6-0, 7-5
Darya Kasatkina (RUS x26) bt Markta Vondrousov (CZE) 7-6 (7/1), 6-4
Hsieh Su-Wei (TPE) bt Taylor Townsend (USA) 6-0, 2-6, 6-3
Alize Cornet (FRA) bt Barbora Strycova (CZE x20) 6-4, 6-1
Agnieszka Radwanska (POL x9) bt Alison Van Uytvanck (BEL) 6-7 (3/7), 6-2, 6-3