INDIAN WELLS: Germany's Philipp Kohlschreiber stunned Australian Open champion Novak Djokovic 6-4, 6-4 on Tuesday, claiming his first career win over a world No. 1 player to reach the fourth round of the ATP Indian Wells Masters.
Serbian superstar Djokovic was playing his first tournament since lifting a record seventh title in Melbourne, taking his tally of Grand Slam victories to 15.
He had won eight of nine prior meetings with Kohlschreiber, but could find no answer to the 39th-ranked veteran, who had come up empty in 11 prior attempts to beat a top-ranked rival.
"It's a very special moment," Kohlschreiber said. "Of course, playing the top guys is always a big pleasure, but most of the time they beat you."
In match that resumed after rain stopped play just one game in on Monday night, Kohlschreiber said the warmer daytime conditions suited him better, and Djokovic agreed.
"I liked my chances more at night against Kohlschreiber," Djokovic said. "Completely different conditions today: Ball bounces much higher.
"Obviously he uses his spin very well. I wasn't playing well. One of those days," added Djokovic, whose defeat came on a day the women's draw lost it's top two seeds -- world number one Naomi Osaka and number two Simona Halep.
"I congratulate him for playing tactically really well and getting me out of my comfort zone," Djokovic said. "He deserved to win."
After dropping the first set, Djokovic displayed his frustration by banging his racquet against his foot until it crumpled. The fit of pique did nothing to improve his fortunes as Kohlschreiber opened the second set with a break.
Two wayward forehands and a double fault from Djokovic helped Kohlschreiber to another break for a 5-2 lead.
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Then it was Kohlschreiber's turn to show some nerves as a string of four errors, including a double fault, gave Djokovic a break back.
He made no mistake on his second chance, however, firing a sideline-skimming forehand to seal the milestone win on his first match point.
Kohlschreiber will face France's Gael Monfils for a place in the quarter-finals.
Djokovic will try to regroup for the Miami Masters after the abrupt end to his bid to win a record sixth Indian Wells title and match Rafael Nadal's record of 33 Masters 1000 titles.
World number two Nadal stayed on track to improve that number as he swept past Argentine Diego Schwartzman 6-3, 6-1 to reach the last 16.
Nadal took his record against the world No. 26 to 7-0 in emphatic style, never facing a break point in a match lasting an hour and 16 minutes.
"I think I played a very solid match. I did a lot of things well," Nadal said.
Nadal, a three-time winner of the Indian Wells title, next faces Serbian qualifier Filip Krajinovic, who ousted 14th-seeded Russian Daniil Medvedev 6-3, 6-2.
Fourth-seeded Roger Federer eased through with a 6-3, 6-4 victory over friend and fellow Swiss Stan Wawrinka.
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Federer took his record to 22-3 over Wawrinka, a former world number three who is climbing back up the rankings in the wake of double knee surgery.
"I felt good from the beginning," said Federer, who is coming off his 100th career title at Dubai last month. "For me, the plan worked. I was able to mix up my game, cover my serve, be dangerous on the return -- maybe take some rhythm away from Stan.
"You can't always make it work. Tonight it worked well so I think it was a good match for me," said Federer, who like Djokovic is a five-time winner at Indian Wells.
Federer next faces Britain's Kyle Edmund, who beat Macedonian qualifier Radu Albot 6-3, 6-3.
Poland's 67th-ranked Hubert Herkacz upset sixth-seeded Kei Nishikori of Japan 4-6, 6-4, 6-3 to reach the last 16 of a Masters 1000 event for the first time.
He will play 19-year-old Canadian Denis Shapovalov, the 24th seed who beat 10th-seeded Croatian Marin Cilic 6-4, 6-2.