Germany's Tommy Haas came from a set down to upset 11th-seeded Andy Murray 2-6, 7-5, 6-3 in Wednesday's fourth round and maintain his impressive run at the Pacific Life Open.
The 29-year-old, making the most of his unexpected good health, knocked out sixth-seeded Andy Roddick earlier in the week and will next meet top seed Roger Federer or Croat Ivan Ljubicic in the quarter-finals.
A former world number two whose career has been hampered by a series of injuries and surgeries, Haas has taken great delight in experiencing no pain at Indian Wells Tennis Garden.
"Every day is just important to feel kind of healthy, going out there and hitting my shots and my serves without feeling anything in my shoulder," the Hamburg native told reporters.
"I need to keep telling myself that that's really the most important thing for me. On top of that, playing a great week until now and hopefully more, it's worth going through a lot of pain.
"As long as my shoulder stays strong and I don't feel too much pain, I can go out there and compete and I can be tough," added Haas, who won the most recent of his 11 ATP titles in Memphis last year.
"It's all coming together here in some sort of way. You kind of wait for that moment where you start to feel good again, and it's been going pretty well this week."
Haas, who had surgery on his right shoulder for a third time in November, was elated to beat Murray, who triumphed in their only previous meeting at Indian Wells last year.
"It's nice to get your revenge back at the same place, pretty much," said the German, who lost to Murray at the same stage 12 months ago.
"It took a year for us to go back and battle at it again. It was another great match, very exciting, and it just came down to a few big points here and there.
"You know, I saved a lot of break points in the third and so did he. But I came up with the goods at the right time, which was great."
Murray, who has won ATP titles this season in Marseille and Doha, was frustrated after playing too defensively in the third set.
"I didn't serve well enough today," the 20-year-old Scot said.
"I was a bit too defensive on the break points in the third set even though, to be fair to him, he did serve very well on a lot of them and didn't give me any cheap points. So credit to him for that, but I was a bit too defensive."