British number one Heather Watson pulled off the biggest win of her career in Indian Wells, beating Agnieszka Radwanska in straight sets.
Watson, 22, who had never previously taken a set off the Polish world number eight, won 6-4 6-4 in the third round at the BNP Paribas Open.
It is the first time that Watson, ranked 43, has beaten a player in the world's top 10.
"I am delighted," said Watson. "She is a great player and I needed my A-game."
Watson, who will face Carla Suarez Navarro or Anastasia Pavlyuchenkova in round four, lost to Radwanska in last year's second round in California.
After being broken early on, Watson went on to dominate the opening set, breaking her opponent twice and regularly getting the better of some lengthy backhand exchanges.
The Briton produced a blistering ace to wrap up the set and then broke her opponent at the start of the second set as she moved 2-0 up.
Radwanska, last year's beaten finalist, belatedly found some form and hit back, breaking twice to move 4-2 ahead.
But Watson - who had never previously been further than the second round in Indian Wells - recovered her composure to win four straight games herself.
Leading 5-4, she served out to love to wrap up a superb victory and reach the last 16.