INDIAN WELLS, California (Reuters) - World number one Victoria Azarenka and Maria Sharapova stayed on track for a mouth-watering showdown in the final of the Indian Wells WTA tournament while defending champion Caroline Wozniacki was beaten by Ana Ivanovic on Tuesday.
Top-seeded Belarusian Azarenka eased into the last eight with a ruthless 6-3 6-1 demolition of Germany's Julia Goerges before Russia's second seed Sharapova swept past Italian Roberta Vinci 6-2 6-1.
Dane Wozniacki, however, was ousted by 2008 winner Ivanovic, who produced sizzling tennis from the baseline to triumph 6-3 6-2 in the fourth round. The Serb will next meet seventh seed Marion Bartoli of France after she breezed past Czech Lucie Safarova 6-1 6-4.
In dazzling afternoon sunshine, Azarenka broke Goerges three times in each set before sealing victory with an ace to end the match in just over an hour on the showpiece stadium court.
The pony-tailed Belarusian won her first grand slam crown at the Australian Open in January and is 20-0 this year. She will next face fifth seed Agnieszka Radwanska of Poland.
Radwanska, who won her eighth WTA title in Doha last month, advanced when American wild card Jamie Hampton retired with cramp when trailing 6-3 4-6 3-0.
"I take it day by day and after that we will see what happens," Azarenka told reporters of her perfect start to the season. "I have to keep my focus on every moment, every day."
The 22-year-old has launched her 2012 campaign with three WTA titles and said complacency was not in her vocabulary.
"I always try to work on different things because I think there is never really a limit to what you can achieve," Azarenka added. "You can always try to do better. It may not work right away, but at least you can start the process."
Asked what had been the most improved department of her game this year, she replied: "The thing that really stands out is my physical condition, and I'm pleased with that. But I feel like there is so much more room to improve."
Sharapova had needed five match points to beat Romania's Simona Halep in the previous round but stepped up a few gears against Vinci, breaking her six times before completing victory in just over an hour.
Ivanovic booked her place in the last eight after breaking Wozniacki three times in the opening set and twice in the second, leaping into the air in delight when she clinched victory after one hour 10 minutes.
"I'm very happy," the 24-year-old Serb said after beating the Dane for the first time since the 2008 French Open, which she went on to win.
"I didn't do much wrong today besides the first few games on my serve. I'm really pleased the way I was aggressive."
Radwanska, who reached the quarter-finals for a third time at Indian Wells, applauded Hampton's effort.
"She was playing very good today and I was really in trouble in the second set," the 23-year-old said. "She was really hitting the ball very well and moving very well.
"I just noticed when she fell down. It was obvious that she was cramping and it's always tough when you can't really have a medical timeout for that and you're losing points or games like today.
"When somebody is losing two or three games, it's really a lot. It's tough to come back."
In other matches, eighth seed Li Na of China) crushed Czech Klara Zakopalova 6-1 6-0, Maria Kirilenko beat fellow Russian Nadia Petrova 6-1 5-7 6-2 and Germany's Angelique Kerber edged past American Christina McHale 6-3 3-6 7-6.
Reporting by Mark Lamport-Stokes; Editing by Peter Rutherford