Another 37-year-old had a good opening day as Roger Federer marked his return to Roland-Garros for the first time since 2015 with a straight-sets dismissal of Italian Lorenzo Sonego, 6-2, 6-4, 6-4 on Court Philippe-Chatrier.
The Swiss remains undefeated in Grand Slam first-round matches since he fell to Luis Horna in his opener at Roland-Garros in 2003.
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Former world No.3 Grigor Dimitrov halted a spirited comeback from another ex-top-tenner, Janko Tipsarevic, to defeat the Serb 6-0, 6-3, 3-6, 6-7(4), 6-4 and book a tricky second-round meeting with No.11 seed Marin Cilic. It was only the 10th main-draw victory of the season for Dimitrov, who has slipped to No.47 in the world hampered by a shoulder injury.
"To play Grigor in the second round is one of the toughest draws," Cilic told reporters on Sunday. "I have to prepare the best I can and to play my level of tennis and try to play as good as I can.
"And I know that Grigor didn't have as many wins as we would expect him to see, but I still think that his level is good. He's playing really good and maybe just that one or two matches here and there can make a difference."