Serena Williams made her first appearance at the French Open to support sister Venus but Petra Kvitova's comeback tournament is over.
The two-time Wimbledon champion made an emotional return to tennis on Sunday with victory over Julia Boserup five months after she was stabbed by an intruder.
The result was secondary, with Kvitova and her doctors having feared she would never play professionally again, but the Czech was much closer to her best level than had been expected.
Kvitova looked in good shape again early on against Bethanie Mattek-Sands in round two but the American fought back to win 7-6 (7/5) 7-6 (7/5).
Kvitova had led 3-1 in the opening set with points for 4-1 and a double break but Mattek-Sands dug in very well, saving 10 of 14 break points during the match.
The American, ranked 117, then recovered from 4-2 down to win the tie-break before taking a 10-minute break for treatment to her thigh.
Kvitova sat with her head in her towel, and the disruption seemed to affect her as she dropped serve in the opening game of the second set.
She pulled back level but was edged out in another tie-break, bouncing her racket in annoyance after serving a double fault on match point.
But Kvitova will leave Paris with far more positive feelings than negative and could yet be a major force on grass, her favourite surface.
Meanwhile, Serena continued her maternity leave tour of major sporting events by visiting the tournament she has won on three occasions.
The 35-year-old, who is expecting her first child in the autumn, was at the Monaco Grand Prix on Sunday before heading to Paris, where she has an apartment.
Serena cheered on Venus Williams from the players' box on Court Philippe Chatrier, and there was plenty for the Williams family to celebrate as the 10th seed eased to a 6-3 6-1 win over Kurumi Nara.
Defending champion Garbine Muguruza continued to pick her way through a nightmare draw with a terrific victory over Anett Kontaveit.
The Estonian has been one of the revelations of the clay-court season and had Muguruza in all sorts of trouble at a set and a break down.
But Muguruza might just be playing herself into form again at just the right time following a year of struggle and powered her way to a 6-7 (4/7) 6-4 6-2 victory in two hours and seven minutes.
Things do not get any easier for the Spaniard, who next plays 27th seed Yulia Putintseva.
It was not a good day, though, for Ekaterina Makarova, conqueror of top seed Angelique Kerber in round one but knocked out 6-2 6-2 by Lesia Tsurenko in round two.
Former US Open champion Sam Stosur did make it through to round two, the 23rd seed beating Kirsten Flipkens 6-2 7-6 (8/6).
There was a notable victory, meanwhile, for 18-year-old American Cici Bellis over last year's semi-finalist Kiki Bertens.
Bellis is making her main-draw debut at the French Open and saw off 18th seed Bertens 6-3 7-6 (7/5).
Tunisian Ons Jabeur became the first Arab woman to reach the third round of a grand slam with a 6-4 6-3 upset of sixth seed Dominika Cibulkova.
Jabeur, the 2011 junior champion at Roland Garros, lost in qualifying but was given a lucky loser spot and has made the most of her chance brilliantly.
France's big hope Kristina Mladenovic had a much less dramatic afternoon than in her first-round match, easing to a 6-2 6-3 win over former finalist Sara Errani.
