PIX: Djokovic takes first unsteady step toward calendar slam

Images from Day 2 at the US Open.

Novak Djokovic took a first unsteady step toward completing the calendar-year Grand Slam on Tuesday as the Serb laboured into the second round of the US Open with a 6-1, 6-7(5), 6-2, 6-1 win over dashing Danish teenager Holger Rune.

On paper, the contest was a total mismatch - an 18-year-old qualifier making his Grand Slam debut against a player chasing a 21st major title.

While the outcome was exactly what was expected, the effort needed by Djokovic to see off the fearless Dane, who battled to the end despite suffering cramp, was not.

"I started great. Played a really, really good first set," said Djokovic. "After that, I don't know, I was 4-3 serving in the second set, everything was working well, but then I just lost the first serve.

"I had until tonight tons of experience playing on this court, for him it was the first one.

"Still you get nerves. You still are feeling a little bit rusty at the beginning."

The match got underway amid a somewhat flat atmosphere inside Arthur Ashe Stadium but the crowd were chanting the little-known Dane's name after he stunned Djokovic to win the second set.

Aside from that, it was a controlled effort from the 34-year-old Djokovic, far different from the Serb's last match on Arthur Ashe Stadium court which ended with him being disqualified after swatting a ball in frustration that struck a line judge.

The stone-faced world number one was all business from the start, breaking his opponent at the first opportunity and rolling through the set in just 26 minutes.

Playing his first event since a disappointing Tokyo Olympics there were signs of rust and a lack of intensity, particularly in a sloppy second set when Rune broke him twice and forced the set to tie-break that he easily won.

But there was never any panic from Djokovic, who turned up the pressure in the third with an early break to regain control as Rune began to suffer cramp.

As Rune grimaced with every step, Djokovic showed his ruthless side, moving the youngster from line-to-line and taking the set 6-2.

Rune was determined to battle his way to the end but a Djokovic victory was now certain and the Serb wrapped up the match by taking the fourth set 6-1.

Andreescu outlasts Golubic

Bianca Andreescu overcame stomach pain and a stiff challenge from Viktorija Golubic to advance 7-5, 4-6, 7-5 into the second round of the US Open on Tuesday.

The 21-year-old, making her return to Arthur Ashe Stadium for the first time since she won the tournament in 2019, got all she could handle from the Swiss in the nearly three-hour affair on a hot and humid night in New York.

But the sixth-seeded Andreescu's seven aces and punishing groundstrokes ultimately proved too much for Golubic.

The Canadian yelled "Come on" and pumped her fist after Golubic sent a forehand wide on match point to seal the win.

Few knew what to expect from Andreescu coming into the year's final Grand Slam tournament.

After defeating Serena Williams in the 2019 final, Andreescu's 2020 Grand Slam campaign was written off by injury and sickness that included everything from tearing the meniscus in her left knee to testing positive for COVID-19.

This year, she has managed just one win at a Grand Slam tournament - a first-round victory over Mihaela Buzarnescu at this year's Australian Open.

That was followed by first-round exits at both the French Open and Wimbledon.

"It's definitely emotional," Andreescu said in an on-court interview after the match.

"I didn't play here last year and I honestly didn't play anything in 2020. I've been struggling a lot this past year so for me, I'm just thinking about all those struggles and how it's all worth it.

"Winning on this court again is just incredible."

Andreescu needed a medical time out midway through the second set to attend to an upset stomach, but said it turned out to be fine.

"My food was just rumbling in my stomach and I felt like I had to throw up, which is random because I ate like, five hours ago," she said.

"It was totally fine after a couple games but it was a little tough."

Next up for Andreescu is a second round clash with American Lauren Davis on Thursday.

Barty made to sweat in win over Zvonareva

World number one Ash Barty was made to sweat for a 6-1, 7-6(7) win over Vera Zvonareva and a spot in the second round.

The top-seeded Australian came out firing on all cylinders and raced to a 3-0 lead in a rapid-fire opening set that was over in 24 minutes.

But what looked to be a straightforward afternoon for Barty turned tense in a grinding second set which the 36-year-old Zvonareva forced to a tiebreak before falling 9-7.

"Vera, without a doubt she's an experienced campaigner," said Barty. "I think in the first set I served exceptionally well.

"She was a little bit loose off her racquet and she gave me a few cheapies.

"I think all in all being able to work my way around that and kind of get through that in straight sets was really pleasing.

"I think when my back was against the wall I came up with some really good stuff.

"That's all we can ask when your back is against the wall."

Barty has won five tournaments this season, including a second career Grand Slam at Wimbledon and her U.S. Open tune-up in Cincinnati.

In between those two victories, however, the 25-year-old threw in a dismal performance when she was booted out of the opening round of the Tokyo Olympics by 48th-ranked Sara Sorribes Tormo.

Zvonareva is a former US Open and Wimbledon runner-up but her best results came more than a decade ago and the injury-ravaged Russian has had spotty performances at Grand Slams ever since, not advancing past the second round of any major since 2014.

She embraced her moment back on Arthur Ashe Stadium court, refusing to wave the white flag after a lopsided opening set.

In the end Barty's all-court game and power proved too much for her, with the Australian laying down 11 aces and firing 31 winners compared to nine by her opponent.

Shapovalov eases through to second round

Canadian Denis Shapovalov served up 14 aces to make easy work of Argentine Federico Delbonis and win 6-2, 6-2, 6-3 in the first round.

The seventh seed was up a break after the fifth game in the first set and held on to the momentum, firing off 38 winners to Delbonis's 11 across the entire match and winning 90% of his first-serve points.

Shapovalov never faced a break point and was the clear favourite of the crowd in Louis Armstrong Stadium, who chanted "Let's go Shapo" late in the third set from stands that sat empty a year ago when he reached the quarter-finals for the first time at Flushing Meadows.

The win snapped a four-match losing streak for the world number 10, who fell to 20-time Grand Slam winner Novak Djokovic in the Wimbledon semi-finals earlier this year before bouncing out of his opening matches in Gstaad, and the Toronto and Cincinnati Masters.

Olympic champion Bencic cruises into second round

Belinda Bencic, playing with a new found sense of freedom after winning a gold medal in the singles competition at the Tokyo Olympics, breezed past Dutchwoman Arantxa Rus 6-4, 6-4 to reach the second round.

Bencic, who reached the US Open semi-finals in 2019 and sat out last year's tournament amid the COVID-19 outbreak, used a solid service game to improve to 3-0 all-time against the left-handed Rus.

Asked in an on-court interview what pleased her most about the win, Bencic, who did not face a break point during the 90-minute match, replied "Definitely my serve.

"She (Rus) is a great player, she makes it really hard for me to play against her, the typical lefty game, and I've played a lot of lefties in the last couple of matches so I was a little bit prepared."

Bencic, who is seeded 11th, broke Rus in the first game of the match en route to taking the opening set and again in the second set to go ahead 3-2 before wrapping up the match by forcing a forehand error.

The 24-year-old Swiss, who will face Italy's Martina Trevisan in the second round, said she had been more relaxed on court since her Olympic triumph.

"I kind of achieved my dream in Tokyo. I'm so kind of happy and I'm sure it was my proudest moment which I will ever achieve," said Bencic.

"I feel like it gives me a lot of calmness and just relaxing and I can really play just very free now and I'm playing for fun. "I am feeling good on the court right now so I am not putting any pressure on myself."