Novak Djokovic's bid to become the first man in half a century to win all four Grand Slam titles twice got off to a straightforward start at Roland Garros as a 'double bounce' row prompted calls for video replays to be introduced in tennis.
World No 1 Djokovic, returning to Grand Slam action for the first time since his US Open disqualification, eased past Sweden's Mikael Ymer, ranked 80, in straight sets 6-0, 6-2, 6-3.
It was his 32nd win in 33 matches in 2020 and kept him on course for a second French Open title following his 2016 triumph, and 18th career major.
"It's always a pleasure to return to Paris on Philippe Chatrier, this important court. The atmosphere is a little different this year with few fans but I remain motivated to win the title," said Djokovic, only one of two men to have defeated 12-time champion Rafael Nadal in 15 years in Paris.
Djokovic, who suffered no immediate hangover from his US Open controversy by quickly wrapping up a record 36th Masters title in Rome on the eve of Roland Garros, next faces Lithuania's Ricardas Berankis.
The 33-year-old Serb is in the second round for a record-equalling 16th time, matching Guillermo Vilas and Nadal.
Kristina Mladenovic called for a football-style VAR system to be introduced in tennis after her opponent profited from a double bounce to help knock the Frenchwoman out of her home Grand Slam.
Mladenovic was 5-1 up and with a set point against Laura Siegemund when the German scooped a winner despite the ball appearing to bounce twice. The incident was missed by chair umpire Eva Asderaki.
World No 44 Mladenovic pleaded in vain before Siegemund took full advantage, racing into the next round with a 7-5, 6-3 win.
"It would be great to have that," said Mladenovic when asked if video replays should be introduced.
"It'd be a pity to replace a human with a camera but to err is human. I don't see how the umpire could not see it. Unfortunately, she continues at Roland Garros but I do not."
Siegemund defended her actions.
"If in that call, I'm coming running full speed, if in that call I say, 'Oh, it was a double bounce,' and later I see on the video it was not, I would be angry at myself. So I think in that situation, that was a close call," she said.
"That's what the umpire is there for. I think she has better chances than me to see what has happened exactly."
World No 172 Sherif took the first set off second seed Karolina Pliskova in Tuesday's Roland Garros first round but could not sustain her challenge in a 6-7 (9/11), 6-2, 6-4 loss.
Sherif came through qualifying in Paris to join Tunisia's Ons Jabeur in the 128-player field, the first time two Arab woman have contested the main draw of a major since 2002.
Despite an early exit Sherif, who began 2019 unranked after graduating from Pepperdine University in the US, insisted she had a "huge margin to improve".
"I saw what the level is and I saw not playing my best how close I was to beat one of the best players in the world," she said, grateful to also have the backing of a national icon.
"For Mo Salah, he's one of the best football players in the world, and to see someone very successful supporting other successful people in his country, it just gives you some energy just to know that there are good people out there and people who are already successful are willing to support you."
Latvia's Ostapenko, the world No 43, won her first match at the French Open since sweeping to her shock 2017 title when she fired 46 winners past Madison Brengle of the United States to win 6-2, 6-1.
"After I won here it was a tough time. I had to get used to the pressure but now it's all gone," said the 23-year-old Ostapenko.
Denmark's Clara Tauson, just 17 and a qualifier, unleashed 48 winners to knock out American 21st seed and US Open semi-finalist Jennifer Brady 6-4, 3-6, 9-7. Tauson also saved two match points on her way to a maiden career main draw win.
Australian Open champion Sofia Kenin recovered from a break down in the final set to defeat 125th-ranked Russian Liudmila Samsonova 6-4, 3-6, 6-3.
Fourth seed Kenin, who dumped out Serena Williams in Paris a year ago, fought back from 2-0 down in the decider to advance to a second-round tie against Romania's Ana Bogdan.
