Images from the US Open men's singles first round matches, at Flushing Meadows, New York, on Monday.

Rusty Djokovic kicks off record bid with Albot thrashing

Novak Djokovic's bid for a record 25th Grand Slam title kicked off on Monday with a rusty 6-2, 6-2, 6-4 win over qualifier Radu Albot in the U.S. Open first round as the defending champion returned to the court after his Olympic triumph.

Three weeks after winning the singles title at the Paris Games, Djokovic toted his rackets and gear in a pair of gold-coloured bags onto centre court where the Arthur Ashe Stadium crowd gave him a hero's welcome.

But the Serb's golden touch with decidedly lacking in the late night match as he struggled with serve and racked up nearly twice as many unforced errors as winners.

For all that, he had more than enough weapons to handle Moldovan Albot in their first tour clash and claim a record 78th win at Arthur Ashe under a closed roof.

"I was not aware of it, to be honest with you," Djokovic said of the centre court milestone.

"It's definitely the loudest stadium we have in the history of our sport. The night sessions are the best in the world here."

While having never played Albot before, Djokovic said he had done his homework on the 34-year-old who beat both his younger brothers Marko and Djordje during their playing days.

"They both lost to him so hopefully I can avenge my brothers tonight," he told ESPN commentator Brad Gilbert with a laugh before taking the court.

Djokovic duly avenged the family name in three clunky sets but he will hope for better from his game as he looks to move past Margaret Court on the all-time Grand Slam winners' list.

With 10 double-faults, his serve was wild by his usual standards, and he winced throughout the night as 40 unforced errors piled up.

His coach Nena Zimonjic was an animated presence, barking instructions in Serbian at the wayward champion, who could convert only six out of 16 break points.

Though Djokovic was well off his best, Albot was unable to make the world number two pay.

After bright starts in the first two sets, he crumbled on serve in each of them before making a better game of the third.

In the twilight of a record-smashing career, Djokovic is eyeing several milestones in New York, including a fifth title at Flushing Meadows to match the professional era record held by Pete Sampras, Jimmy Connors and Roger Federer.

He also hopes to become the first back-to-back winner in the men's singles since Federer's run of five successive titles from 2004-08.

Former champ Thiem whipped by Shelton

Former champion Dominic Thiem's final appearance at the US Open ended tamely on Monday after he was beaten 6-4, 6-2, 6-2 in the first round by Ben Shelton of the United States.

The Austrian has struggled to reproduce the form that carried him to the 2020 Flushing Meadows title and announced he would retire from the sport this season after being troubled by a wrist injury in recent years.

Shelton leaned on his powerful forehand and sent over eight aces to open the action on Arthur Ashe Stadium, as the 21-year-old hopes to recapture the magic of his charmed run to the semi-finals 12 months ago.

Despite struggling with his serve, Thiem showed he had some fight left in him as he fended off two break points in the 10th game but a relentless Shelton forced him into an error to break him on the third attempt to take the opening set.

The American extinguished Thiem's lone break-point opportunity in the opening game of the second set and the Austrian handed Shelton a break in the second game with a double fault and an unforced error.

Shelton showed he could be a threat over the next two weeks as he broke Thiem again to close out the second set. He ran away with the match in the third set, pummeling 34 winners in a confident performance.

"Not much better atmosphere than being here at Ashe," said Shelton, who will next play Spain's Roberto Bautista Agut. "I'm glad that I had the opportunity to open it up here."

Thiem, who hoisted the trophy in front of empty stands in the midst of the COVID-19 pandemic, stayed back on court for ages on Monday to sign memorabilia for fans.

"I am super happy I got the chance to play my last US Open match on this court," Thiem said.

"I can now spend some time with you guys to say thank you to all of you and to make the time up that we missed four years ago."

Tiafoe beats fellow American Kovacevic

Frances Tiafoe held off fellow American Aleksandar Kovacevic to come away with a 6-4, 6-3, 4-6, 7-5 win in the first round.

Tiafoe, seeded 20th, remained composed, even as the pressure ramped up, to advance as he looks to make good on his promise to win his home Grand Slam after his scintillating run to the semi-finals two years ago put him firmly on the map.

Kovacevic, a New York native making his US Open debut, looked a little nervy serving in the 10th game of the opener and Tiafoe took full advantage, leaping high in the air to pound an overhead and grab the first set.

Tiafoe smoked a service return for a 4-2 lead in the second and took a 2-0 lead when Kovacevic's one-handed backhand sailed long.

Kovacevic came to life in the third, hitting a sensational around-the-net forehand winner in the fourth game to peel off some of the support from the pro-Tiafoe crowd and breaking serve for a second time to force a fourth set.

But Tiafoe would not be denied, breaking for a 6-5 lead in the fourth and converting his fifth match point to seal the win.

Thunderstorms forced the closure of the roof on Louis Armstrong Stadium and Tiafoe said the change in conditions had a big impact.

"It got pretty tough there at the end," Tiafoe said.

"When they closed the roof it was really muggy in here. I was really struggling breathing midway in the third and most of the fourth.

"At the end of the fourth I started feeling much better and I was trying to do everything I could to finish in four. But definitely tough, muggy conditions tonight."

Tiafoe has struggled to find momentum and wins this season but has looked sharper of late, reaching the final of the Cincinnati Open last week to break back into the top 20.

"Cincinnati was such a great week, I’m just trying to gain steam from that," he said.

Next up for Tiafoe is a second-round meeting with Alexander Shevchenko of Kazakhstan.

Zverev flexes big serve in takedown of Marterer

Fourth seed Alexander Zverev out-duelled fellow German Maximilian Marterer 6-2, 6-7(5), 6-3, 6-2.

Zverev flexed his dominant serve, blasting 21 aces and winning 79 percent of his first serve points on the Grandstand.

Unseeded Marterer, the "lucky loser" that entered the draw after Emil Ruusuvuori withdrew last week, captured a close second set but was ultimately overpowered by the world No. 4.

Zverev looked sharp in the first set, breaking his opponent's serve in the opening game before Marterer battled back to claim a back-and-forth second set in a tiebreak.

The big-serving Zverev looked frustrated at times, tossing his racket at the start of the third set after committing one of 44 unforced errors.

The win sets up a second round clash with Frenchman Alexandre Muller, who beat Australia's Adam Walton 3-6, 7-6(9-7), 6-3, 6-4 later on Monday.

Fritz breezes past Carabelli

Taylor Fritz leaned on his dominant forehand to beat Argentine Camilo Ugo Carabelli 7-5, 6-1, 6-2 and reach the second round.

World number 12 Fritz, the highest ranked of 17 American men in the main draw, won 79 percent of points on his first serve and converted seven of 11 break-point chances to secure victory on Louis Armstrong Stadium.

In the first meeting between the two players, Fritz needed a bit of time to find his rhythm and was made to come back from an early break down before securing the opening set when he broke Carabelli for a third time.

The second set was all one-way traffic as Fritz faced just one break point while building a 5-0 lead before Ugo Carabelli finally held serve only for the American to close out the frame on his serve.

With victory in sight and the home crowd firmly on his side, Fritz broke at love to go 3-2 up in the third set and broke again before serving out the match with a love hold that was capped with a pair of aces.

Up next for Fritz, looking to become the first American man to win a Grand Slam title since Andy Roddick at the 2003 US Open, will be a clash with Italy's Matteo Berrettini, who beat Spain's Albert Ramos Vinolas 7-6(2), 6-2, 6-3.