Defending champion Rafael Nadal was a surprise casualty at the BNP Paribas Open as he suffered a three-set loss to Alexandr Dolgopolov in Indian Wells on Manday.
The world No 1 had won all five of his previous meetings against the Ukrainian – including in the final of the Rio Open a fortnight ago.
However, Dolgopolov gained revenge as he held his nerve to claim a 6-3 3-6 7-6 (7-5) victory – although Nadal blew a 4-2 lead in the deciding tiebreak.
Dolgopolov, the 28th seed, will now face No 13-ranked Fabio Fognini after the Italian ground out a 6-2 3-6 7-5 victory over Gael Monfils, staving off a match point in the third set.
"I feel great, I mean, as after every win, of course," Dolgopolov said. "This one was bigger, and I beat the defending champion, number one in the world.
"I guess I just need to enjoy this evening andforget about it tomorrow and try to compete in the rest of the tournament. I'm still in."
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Nadal, who also won the title in Indian Wells in 2007 and 2009, insists he will now turn his attentions to the Sony Open.
"I'm going to keep working hard to try to be ready to play better in Miami."
Australian Open champion Stanislas Wawrinka came through his third round encounter unscathed, with a 6-0 6-2 victory over Andreas Seppi.
Fellow seeds Kevin Anderson and Milos Raonic are also through to the next round.Anderson, ranked 17th, came from a set down to beat Evgeny Donskoy 4-6 6-0 6-3, while No 10 seed Raonic ousted Alejandro Falla 6-4 6-3.