Serena Williams made it 21 wins on the bounce with an easy victory over Dominika Cibulkova to reach the quarter-finals of the WTA Italian Open.
The world No 1 beat the Slovakian 14th seed 6-0 6-1 to set up a last-eight clash with Spain's Carla Suarez Navarro.
But the American is taking nothing for granted ahead of the game with the unseeded Navarro, who beat Lourdes Dominguez Lino 6-2 6-3 to reach the quarter-finals.
"Nothing is ever perfect - I learned that last year when I felt perfect," said Williams, referring to her stunning first-round loss at the French Open in 2012.
"I am still in the danger zone."
Williams added: "I can't remember the other winning streaks, but I hope I can get to 22 and the rest of the matches that I have here.
"Plus seven, and Wimbledon too, so it would be dangerous to lose now."
Second seed Maria Sharapova, winner of the last two editions of the tournament, out-hit Sloane Stephens 6-2 6-1 in just over an hour.
She will play Sara Errani, the last remaining Italian in the tournament who advanced when 12th-seeded Maria Kirilenko of Russia retired with a left knee injury while trailing 6-3 2-0.
Unseeded two-time champion Jelena Jankovic upset 2011 Roland Garros winner Li Na, the Chinese fifth seed, 7-6 (7/2) 7-5.
"I felt like I wasn't playing so badly today, it was just a really long, tough match between me and JJ," Li said. "I was trying a lot of things out there on the court today. Sometimes it was working, sometimes it didn't."
Jankovic will next face Romanian qualifier Simona Halep, who beat 13th-seeded Roberta Vinci of Italy 6-4 6-2.
Third-seeded Victoria Azarenka also went through when Ayumi Morita retired through injury in the second set. She will face ninth seed Samantha Stosur, who beat eighth seed Petra Kvitova 7-5 2-6 6-1.