Serena is going for her eighth title at the All England Club. She beat France's Kristina Mladenovic 7-5, 7-6(2) to set up a match with Russia's Evgeniya Rodina in the fourth round. She has now won 17 straight singles matches at Wimbledon.
Kiki Bertens of the Netherlands upset Venus in three sets, winning 6-2, 6-7(5), 8-6. Bertens battles Karolina Pliskova in the round of 16. Bertens is ranked No. 20 in the Women's Tennis Association world rankings and is the No. 20 seed in the tournament. Venus is ranked No. 9 in the world.
Serena Williams is playing in the tournament as the No. 25 seed, despite being ranked No. 181 in the world.
"I just feel like, 'Okay, I have nothing to lose at this point. I want to try harder.' I think to myself, 'Is this the best that I can do? Can I do more? Lot of things go through my brain.' Sometimes other things go through my brain," Williams told reporters. "I just keep going."
"I don't have anything to lose. I have absolutely nothing to prove. Yeah, everything is a bonus. Every time I step out there, I know what I'm capable of. I know every Grand Slam, I've won 'em, I'm capable of just going out there and enjoying it."
She hit 13 aces in the victory. She broke Mladenovic's serve three times in the 1:49 match.
Top-seeded Roger Federer beat Germany's Jan-Lennard Struff in three sets to advance to the round of 16 on the men's side. American John Isner, Adrian Mannarino, Stefanos Tsitsipas and Mackenzie McDonald also advanced into the fourth round in London.
Evgeniya Rodina knocked off No. 10 Madison Keys on the women's side. Ekaterina Makarova, Julia Gorges, Camila Giorgi, Donna Vekic will join Rodina, Williams, Bertens and Pliskova in the fourth round.
Simona Halep and Pliskova are the only players in the top ten of the rankings to advance into the round of 16 on the women's side.