A summary of Tuesday's action at the US Open.
Karen Khachanov upset Nick Kyrgios 7-5, 4-6, 7-5, 6-7(3), 6-4 at the US Open on Tuesday to reach the semi-finals of a Grand Slam tournament for the first time.
Russian Khachanov, seeded 27th, fired an unreturnable serve on match point to seal the win over the Australian, who had knocked out world number one Daniil Medvedev in the previous round.
Khachanov was better in the intense match's biggest moments, saving seven of the nine break points he faced, often with his thundering serve.
"Crazy match like I was expecting it would be," he said in an on-court interview after his second straight five-set win.
"I am ready to run, to fight, to play five sets. We played again for almost four hours and that's the only way to beat Nick I think."
Kyrgios, known as much for his explosive temper as his blistering serve, came out with surprisingly little energy and dropped the first set when Khachanov hit a perfect lob.
Kyrgios, who has the most wins of any player on Tour since June, received medical attention on his left knee prior to the start of the second set, raising the prospect he might retire from the match when he said he "could not walk".
But he persevered and broke early in the second set, which he claimed with a crosscourt backhand winner as he began to grow more animated, yelling at the players box for encouragement and bringing the crowd to its feet with some spectacular shotmaking.
Khachanov grabbed the third set and the players exchanged breaks early in the fourth to set up a tiebreaker dominated by Kyrgios.
Momentum swung firmly in Khachanov's direction when he broke to open the decider on a backhand error by Kyrgios and continued to hold serve until the finish.
"I tried to stay focused in the match," Khachanov said.
"I had some opportunities in the fourth set but he played an amazing tiebreak and what can I do? I can stay focused and try to win the next set," Khachanov said.
"I'm really proud of myself, I was really focused from the beginning to the end and I got the win."
Wimbledon finalist Kyrgios, who smashed rackets in frustration after the match ended, said he was "devastated" after the loss.
"I feel like I let so many people down," he told reporters.
"These four tournaments are the only ones that matter and I feel I have to start all over again."
Khachanov will next face Norway's Casper Ruud for a place in the final.
In-form fifth seed Casper Ruud pushed past Italian Matteo Berrettini 6-1, 6-4, 7-6(4) to reach the US Open semi-finals with a shot at the world number one ranking still on the line in New York.
The French Open runner-up beat Berrettini on clay in July's Gstaad final and looked just as effective on the hard court, hanging back behind the baseline to absorb the 13th seed's power.
Sprinting through a sublime first set in which he produced just two unforced errors, it looked like Ruud was on track for a blowout victory when he was up 5-1 in the second set.
But Berrettini, who was sidelined a number of times this season due to injury or illness, slowly began to find his usual level and appeared to have cracked the code in the third set when he broke Ruud in the second game and saved four breaks in the third.
Ruud mustered a terrific comeback, breaking Berrettini in the ninth and never trailed in the tiebreak.
"That was (a) better start than I ever had before in a match," Ruud said in an on-court interview, adding that he had to temper his enthusiasm in order to clinch the affair.
"Sometimes you can get a little overexcited and think you can walk on water," he said.
He and third seed Carlos Alcaraz have a chance at seizing the world number one ranking at Flushing Meadows, as current holder Daniil Medvedev crashed out in the fourth round.
"Of course it's a little bit (more) motivation," said Ruud. "I'm trying to go for it, of course."
Garcia demolishes Gauff, extends win streak to 13
France's Caroline Garcia proved too strong for Coco Gauff of the United States as she extended her win streak to 13 matches, dating back to Cincinnati qualifying, with a 6-3, 6-4 victory in the quarter-finals under a closed roof of Arthur Ashe Stadium.
The victory enabled her make her first Grand Slam semi-final, where she will meet Tunisian fifth seed Ons Jabeur, who defeated Australia's Ajla Tomljanovic -- Serena Williams's conqueror -- 6-4, 7-6(4) earlier in the day.
The veteran Frenchwoman wasted no time putting pressure on the teenager, stepping into the court to attack Gauff's second serve and clobbering forehands to race out to a 4-0 lead while rain-soaked fans were still finding their seats at Arthur Ashe Stadium.
The 17th seed captured the first set with an exquisite volley and kept her foot on the gas in the second, breaking Gauff in first game to keep the New York crowd hushed.
The 12th-seeded Gauff's best chance to climb back into the match came when she had a break point opportunity to get back on serve while trailing 3-2 in the second.
But Garcia fired two unreturnable first serves and held after an exhausting rally when Gauff's passing shot sailed long, leaving the 18-year-old looking dejected.
Garcia rolled from there and sealed the win when Gauff's backhand landed in the net on match point.
Since coming back from a foot injury in May, Garcia has won three events on three different surfaces, on clay in Warsaw, where she beat world number one Iga Swiatek, grass in Bad Homburg and hardcourt at the Cincinnati Open.
The French ace hit 24 winners, including four aces, to Gauff's 18 winners (five aces).
Following Tuesday's victory, former world No. 4 returns to the WTA's Top 10. She was ranked as low as No. 79 earlier this summer.
Jabeur ends Tomljanovic's winning run
Tunisian fifth seed Ons Jabeur overcame her own frustrations to reach the semi-finals by beating Australian Ajla Tomljanovic 6-4, 7-6(4), becoming the first Arab woman to make the final four at the New York hard court major.
Tomljanovic survived tennis' biggest spotlight when she beat Serena Williams in a packed, third-round prime time affair on Friday but could not keep up in the quarter-final after Jabeur sent over three aces and 15 winners in the first set.
The Wimbledon finalist has a well-earned reputation as Tunisia's "Minister of Happiness" but found her own good cheer tested as the unforced errors piled up in the second set and she threw her racket several times.
Although she broke Tomljanovic in the opening game of the second set, her grip on the match began to waver as her serve deteriorated and the Australian converted three of four break point opportunities.
"I think I'm going to be fired here from my job, Minister of Happiness," Jabeur joked in an on-court interview.
"Tennis is a tough sport and I apologise for my behaviour... but the racket kept slipping away from my hand."
Tomljanovic handed Jabeur a break with a double fault in the ninth game and whacked the ball into the net on the final point of the tiebreak as the stone-faced Tunisian pumped her fist in a subdued celebration.
"It was kind of tough to kind of manage the frustration," Jabeur said. "She keeps fighting and she makes it tough for me."
