Pablo Carreno Busta booed after 'tanking' third set against Karen Khachanov
Spanish star Pablo Carreno Busta was booed to his chair on Louis Armstrong Stadium after "tanking" the end of the third set of his fourth round clash against Karen Khachanov.
Down 5-1 and facing set point, Carreno Busta made a soft return to Khachanov, before starting to walk off the court before the Russian even made the return.
"He just wants out of this set," commentator Adam Fielder said before the final point.
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"The crowd don't like that - he pretty much just tanked the end of that third set."
Carreno Busta then called for the trainer to come out in the change of ends.
Todd Woodbridge speculated the increased humidity inside Louis Armstrong Stadium could be the reason behind the slump.
Jelena Dokic added that she thought the Spaniard may also have a stomach issue.
Pablo Carreno Busta was seen by a trainer between the third and fourth sets. Getty
"Even after that second set - it was one set all but he didn't look great and he was sweating profusely," she said.
"He has struggled physically we've seen the ice towel out, we can see him taking some tablets. It could even be … I thought maybe the physio was talking about his stomach so it could be a combination of both.
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"That's what we've talked about at the US Open - the conditions can all of a sudden change and you can get these really humid and hot days and he definitely looks like he's struggling."
While Louis Armstrong Stadium has a roof, it is open at the sides. A heavy rainshower swept through the area about an hour earlier, which suspended play on the outside courts.
Carreno Busta won the first set 6-4, before Khachanov rallied to win the second and third 6-3, 6-1.
The tablets Carreno Busta took at the break between the third and fourth sets worked, and he took it 6-4 to take the match to a deciding fifth set.
Karen Khachanov celebrates the win. Getty
Both players were on-serve in the fifth set at 3-2, when Carreno Busta made a crucial error.
Up 30-0, with a wide-open court, he put an overhead smash straight into the net. Khachanov then rattled off five of the next six points to break the Spaniard
He held his next game to love.
Carreno Busta gave Khachanov his first opportunity to win the match off the back of a double fault, but followed it up with a booming ace out wide.
He saved another match point with a crunching forehand winner, before finally holding when Khachanov put two shots long.
Khachanov then made no mistake in his own service game to close out the match and win 4-6, 6-3, 6-1, 4-6, 6-3.
In his post-match interview, Khachanov said he would try and relax before taking on either Nick Kyrgios or Daniil Medvedev in his first US Open quarter finals appearance.
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