World number one Naomi Osaka survived another major scare to reach the third round of the French Open.
The 21-year-old, who is chasing a third consecutive grand slam title, lost the first set 6-0 against Anna Karolina Schmiedlova on Tuesday and was two points from defeat.
Things did not get quite so hairy against former world number one Victoria Azarenka in a high-quality match but the top seed was a set and a break down before recovering to win 4-6 7-5 6-1.
Osaka, who said she had never been more nervous during a match than against Schmiedlova, again made a poor start, with Azarenka winning the first four games.
Two-time Australian Open champion Azarenka has been getting closer to her best form having finally returned full-time to the tour last spring following a bruising custody battle over her toddler son.
She weathered an Osaka fightback to take the opening set, the pair trading ferocious ground strokes, and then opened up a 4-2 lead in the second.
But Osaka has established a reputation as one of the toughest players mentally and she dug her way back into the match before racing out to a 5-1 lead in the decider.
Azarenka put up more resistance at the end but ultimately Osaka was just too strong.
Serena steps up in second round
Serena Williams also had her difficulties in the first round, losing her opening set to Vitalia Diatchenko, but she was much more comfortable in a 6-3 6-2 victory over Japanese qualifier Kurumi Nara.
Williams has been struggling with a knee problem and this is the first tournament since the Australian Open in which she has completed two matches.
She was asked afterwards about a picture taken on the eve of the tournament at Disneyland showing Williams in a wheelchair.
Asked about it after the win over Nara, she said: "I'm not going to get into that. I'm playing, and all's good."
Williams' coach Patrick Mouratoglou, who is also working for Eurosport at the tournament, said: "She didn't have as much time as we expected to prepare for a grand slam.
"Considering the small amount of time she had, I think she did an incredible job and I can see that she is able to compete at a good level so I'm quite happy. Of course, it's not perfect but you can't control everything. I think she did the best she could considering the situation."
Osaka next faces Katerina Siniakova, who knocked out 29th seed Maria Sakkari, while Williams takes on young American Sofia Kenin.
Defending champions through
Defending champion Simona Halep was taken to three sets for a second successive match, this time by Pole Magda Linette, before coming through 6-4 5-7 6-3.
Halep looked to be in control at a set and 5-3 and held three match points but Linette fought back to force a decider. Halep then missed another chance to serve for the match at 5-2 but clinched it moments later.
Halep revealed she is struggling with illness, saying: "I didn't feel that great. I'm a little bit sick. I'm really happy I could fight until the end and win this difficult match."
There were standout victories, meanwhile, for two 17-year-olds, with Amanda Anisimova repeating her Australian Open triumph over Aryna Sabalenka and Wimbledon junior champion Iga Swiatek knocking out 16th seed Wang Qiang.
