Serena Williams and her comeback was cut short by sister Venus at Indian Wells, while world number two Caroline Wozniacki survived.
Playing her first competitive tournament since the 2017 Australian Open, 23-time grand slam champion Serena fell to Venus in straight sets on Monday.
Joining Venus in the fourth round was Australian Open champion Wozniacki, who was less than convincing in the desert.
Meanwhile, defending champion Elena Vesnina was bundled out by Angelique Kerber earlier in the day.
VENUS OUTSHINES SERENA
While all eyes were on Serena, Venus stole the show in her 6-3 6-4 victory.
Venus, the eighth seed, was a class above in the 29th meeting between the Williams sisters – Serena boasting a 17-11 head-to-head record before the blockbuster clash.
The seven-time major winner defeated Serena for the first time since 2014, while claiming her first straight-sets win against her youngster sister since 2008, despite a late stumble.
Venus was leading 5-2 when she wasted a match point and the 37-year-old needed to fend off a break point in the 10th game before closing it out.
WOZNIACKI MUDDLES THROUGH
It was far from convincing as Wozniacki prevailed 6-4 2-6 6-3 against Aliaksandra Sasnovich.
Wozniacki overturned a 4-1 deficit in the opening set as she reeled off five successive games to take the lead.
The Danish star could not stop Sasnovich in the second set, however, as a decider loomed.
But Wozniacki managed to compose herself, regrouping after dropping the opening game before progressing.
Wozniacki, who will face 20th seed Daria Kasatkina for a spot in the quarter-finals, said: "I was struggling finding my rhythm. I didn't really feel comfortable out there today. Didn't really get my game going the way I wanted to."
KERBER DETHRONES VESNINA
Vesnina's title defence was ended by two-time grand slam winner Kerber, who triumphed 7-5 6-2.
After losing the first four games of the match, Vesnina responded by winning five on the bounce for a chance to serve for the set.
But Vesnina never earned a set point as Kerber overcome a marathon first set – saving break points and reeling off the final three games.
The second set was more straightforward for Kerber, who will now play Caroline Garcia in the last 16 after the Frenchwoman eliminated Daria Gavrilova 7-5 6-4.
"I know what to expect. I played against her at the end of last year," Kerber said. "It's another quite big match for me, and I will go out there, try to play like I played the last weeks and try to enjoy the next match."
Reigning US Open champion Sloane Stephens and fourth seed Elina Svitolina were among those to bow out.
21. September 2018
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