Martina Hingis beat second seed Lindsay Davenport 6-3, 1-6, 6-2 to reach the Pacific Life Open quarter-finals in one of several upsets on Tuesday.
Australian Open runner-up Marcos Baghdatis overcame seventh seed Gaston Gaudio 6-7, 6-3, 6-2, Czech teenager Tomas Berdych knocked out number nine Lleyton Hewitt 7-5, 6-3 and Russia's Dinara Safina ousted her fifth-seeded compatriot Anastasia Myskina 6-1, 6-3.
Just two and half months into her comeback after three years off the WTA Tour, Hingis continued her race towards the top of the rankings, showing the quick footwork and inventive play that once made her world number one.
After the taller and stronger Davenport found the range of her big serve and ground strokes in the second set, the Swiss 25-year-old rapidly regained her edge, moving her opponent around the court and retrieving a succession of heavy shots from behind the baseline.
Hingis broke Davenport three times during the set and won the match when Davenport made a mistake on a backhand volley.
Davenport was clearly struggling with a back injury but still gave credit to her longtime rival.
"I don't want to take everything from her," the American told reporters. "I know I had to go for big shots, keep the points short, try not to get into longer rallies. When she gets more confidence, I feel like I have to go for bigger and bigger shots and started missing."
Hingis was thrilled with the victory after going into the match having lost eight of her last 11 meetings with the American.
"To beat Lindsay here in Indian Wells, it probably matters a little bit more than anything else," said Hingis, who lost to Davenport in the 2000 final and now has a 11-14 record against her.
"She lives close by and I know she takes it very seriously. To beat her here, it's great," added Hingis who faces Safina in the quarter-finals.
Baghdatis, who lost to world number one Roger Federer in the Australian Open final, is making his Indian Wells debut and he will take on fellow 20-year-old Berdych in the last eight.
Another youngster, Richard Gasquet of France beat Dominik Hrbaty of Slovakia 6-3, 6-4.
Top seed Federer and second seed Rafael Nadal were scheduled to play later, along with women's top seed Justine Henin-Hardenne and Maria Sharapova.