Similar backhand errors cost him the second and third sets too, as he lost the match 7-5, 6-3, 6-4.
At times, the second seed resembled the player whose dominance of the game was total only 12 months ago. Djokovic was untroubled by his 59th-ranked opponent from Portugal.
"It is always great to celebrate my birthday here", said Nadal.
The second- and third-set wins gave Isner 22 tiebreak wins this season. "But it's an important week for me here, and I think I do need to remain focused above all". I wanted the match.
Nadal next faces compatriot Roberto Bautista Agut for a place in the quarter-finals.
He overcame Jiří Veselý of the Czech Republic 6-3, 6-4, 6-3.
"I played a solid match, hitting very well the ball with the forehand", Nadal said. Physically I don't think it's going to affect me at all. Of Nadal's 97 match wins in best-of-five matches on clay, a whopping 72 of them needed three sets or fewer, including one win in which his opponent retired. Robin is a risky opponent always.
"Today I had experience", Williams told the crowd afterward, "and that helped a lot". The 6-0 6-1 6-0 scoreline amply illustrates how that went. The 2016 quarterfinalist, however, slipped on a tarp at he back of Court Suzanne Lenglen and sustained an ankle injury during his match against Horacio Zeballos.More news: Hundreds demonstrate in Kabul for better security
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The Canadian will now face another Spaniard in Pablo Carreno Busta, who beat Bulgaria's Grigor Dimitrov 7-5, 6-3, 6-4.
Despite a poor start against Argentinian Diego Schwartzman, Novak Djokovic will be advancing to the Round of 16 at the French Open. I'm just trying to enjoy every possible moment that I have next to him when he's here with me and when he's not of course we are in daily contact, calling each other, texting and so forth.
"I went on court thinking it was going to be a tough match".
Tagged one of the pre-tournament favourites after reaching the final in the Madrid and Stuttgart claycourt tournaments, the 13th-seeded Mladenovic is looking to become the first French woman since Mary Pierce in 2000 to lift the Suzanne Lenglen Cup. His lone loss came to Dominic Thiem in the quarterfinals of the Italian Open.
The double Wimbledon victor was disappointed to lose.
No. 3 Stan Wawrinka: The 2015 French Open champ has won only three of 18 matches against Nadal, and only once on clay. He, for sure, is showing good spirits and showing his commitment as much as he can to me and to the team. "I made good progress and am getting better and better", he said. I came here to win the matches.