Andy Murray cut a frustrated figure as he was dumped out of the World Tennis Tournament in Rotterdam by Andrey Rublev on Wednesday.
The three-time grand slam champion obliterated a racquet and loudly chastised himself during his 7-5, 6-2 loss to the Russian fourth seed.
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The former World No.1, now ranked 123rd after a series of hip and groin injuries, competed well in the opening set.
But Rublev clinched a crucial break to go ahead 6-5, before saving two break points as he served it out in the next game.
Looking for just his second win over a top-10 player since returning from career-saving hip surgery two years ago, Murray exclaimed: "I'm totally unprepared for this."
The second set looked as though it would be another tight affair, but Rublev reeled off five-straight games to claim an ultimately comfortable win.
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Rublev managed to avoid the chaos as a number of tops seeds crashed out on Wednesday.
Daniil Medvedev missed his chance to usurp Rafael Nadal as World No.2, losing in straight sets to Dusan Lajovic.
The World No.3 was the top seed for this week's tournament following his run to the Australian Open final, but was dumped out 7-6 (7/4), 6-4 in just over 90 minutes.
Medvedev also destroyed his racquet after being broken in the ninth game of the second set, having a row with the umpire and starting the final game with a point penalty as a result.
The outburst came towards the end of a tense performance from the 25-year-old, which featured eight double faults and 25 unforced errors.
A calm Lajovic served out the 10th game to set up a second-round clash with Borna Coric.
Medvedev and Murray joined World No.7 Alexander Zverev and three-time grand slam winner Stan Wawrinka in exiting the tournament early.
Zverev, 23, was dumped out by Kazakhstan's Alexander Bublik in a shock straight sets 7-5, 6-3 defeat.
The German was seeded third in the tournament but was surprised by 43rd-ranked Bublik in just one hour, 19 minutes.
Bublik, who reached the final of last week's tournament in Singapore, will face Tommy Paul in the second round after the American defeated Italy's Lorenzo Sonego 6-4, 7-6 (9/7).
"Beating Sascha is great," Bublik, who has now won his past three matches against top-10 opponents, said after the match.
"There were ups and downs for both of us throughout the match, I got a bit lucky and I was perhaps a little more consistent. I'm just enjoying playing matches right now."
Wawrinka was knocked out on Tuesday, losing in straight sets 6-4, 7-5 to Russia's Karen Khachanov.
Former World No.4 Kei Nishikori, now ranked 45, followed up his win over seventh seed Felix Auger-Aliassime with a 6-3, 2-6, 7-5 victory over Australia's Alex de Minaur to make the quarter-finals.
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