Second seed Agnieszka Radwanska was sent crashing out in the second round of the Dubai Duty Free Tennis Championship after suffering a 6-4 6-1 defeat at the hands of Flavia Pennetta.
Pennetta, who lost her last three matches against Radwanska in straight sets, looked to be in trouble when the Pole eased into a 4-1 lead in the opening set.
But the world No 22 went on to completely dominate the rest of the contest, dropping just one more game as she booked a quarter-final date with Venus Williams.
"I'm of course really happy. It was the first time I've beaten her in six years - I thought I would never beat her again," Pennetta told the WTA's official website.
"But today I played really well. My idea of what I had to do was clear, and I tried to go for the points all the time. I made a few mistakes in the beginning - I was down 4-1, but every game was a big fight - but I kept going and stayed aggressive and it worked in the end."
Williams eased into the last eight after clinching a crushing 6-2 6-1 victory over Ana Ivanovic in just 56 minutes.
Having landed back-to-back titles in 2009 and 2010, Williams has been unfit to play at the tournament in the last three years, but the 33-year-old stretched her winning run in Dubai to 12 matches in seeing off Ivanovic, who she has now defeated in nine of 11 career meetings.
"I'm just trying to play well every day, take one point at a time and learn from my mistakes every match. I'm trying to go out there relaxed with a clear mind," Williams said.
"I definitely learned a lot from the last time we played each other. I definitely think I approached this match differently."
Another former Dubai champion Caroline Wozniacki is through to the quarter-finals after a 6-4 6-4 win against Annika Beck. The Dane will next face Sorana Cirstea, who defeated fourth seed Sara Errani 6-2 5-7 6-1.
Elsewhere in the second round, Alize Cornet beat Kirsten Flipkens 6-3 6-4 and Jelena Jankovic saw off Lucie Safarova 7-5 6-4 to set up a quarter-final clash with top seed Serena Williams.