Naomi Osaka scrapes through first round as Belinda Bencic and Petra Kvitova cruise: US Open round-up

In the men's draw, Matteo Berrettini eliminated veteran Frenchman Richard Gasquet

Naomi Osaka celebrates a point during her US Open first round win over Anna Blinkova. AFP

If Naomi Osaka is to successfully defend her US Open title, she will need to find a whole new level than the one displayed in the first round on Tuesday.

Osaka got the win but only just, her 6-4, 6-7, 6-2 victory over Anna Blinkova - the world No 84 who had lost both previous main draw matches the US Open - was filled with fightbacks, clutch shots and backs-to-the-wall tennis. In short, it was not entirely convincing from the world No 1.

In what has become a worrying trend for the Japanese star, she began slowly and lacking in intensity, and was broken at the first chance. Blinkova held the lead to claim a 4-1 advantage.

Osaka claimed on the eve of the tournament that she was "healing fast" from her knee injury, but with her left knee sporting a black brace, it appeared as though her movement and mobility were slightly restricted.

Whether it was a newfound focus or she had finally warmed up, Osaka clawed her way back into the match and started to find her shots, those powerful, angled forehands starting to paint the lines as Blinkova was run ragged.

Osaka then reeled off five straight games to clinch the first set. From there, it seemed she was ready to steamroll her opponent.

Instead, Blinkova did well to regroup and there was nothing to separate the two players throughout much of the second set. Osaka was forced to hold her nerve to fend off three set points while serving at 4-5 before forcing the break the very next game.

Again, credit to Blinkova who did not fold and claimed the break straight back to force the tie-break which she won at the second attempt.

Osaka had now been forced into a third set - the first time a defending US Open champion had been taken the distance in the first round.

But rather than wallow in the disappointment, the pendulum swung back the way of Osaka and stayed there. After two tense, tight sets, the top seed was more comfortable in the decider, and although she fended off break points, she was ruthless in taking the ones that came her way.

Breaks in the fourth and eighth game sent Osaka into the second round where she will face recently-crowned Bronx Open champion Magda Linette.

A huge improvement will be needed if Osaka is to keep alive her US Open title defence.

Belinda Bencic, the reigning Dubai Duty Free Tennis Championship holder, enjoyed a far more comfortable outing in her first round assignment, defeating Luxembourg's Mandy Minella 6-3, 6-2.

Bencic, who reached the US Open quarter-finals five years ago at the age of 17, asserted her dominance from the start by breaking in the first game of the match. Another break in the eighth game allowed the Swiss to serve out the opener, which she did to love.

There was no let-up in the second set from 22-year-old Bencic, who claimed successive breaks in the third and fifth games to cruise towards the win.

Bencic, who reached a career-high world No 7 as an 18-year-old before injuries derailed her career, will face France's Alize Cornet in the second round after her 6-2, 6-3 win over Jessica Pegula.

Former French Open champion Jelena Ostapenko produced a morale-boosting win, beating Aleksandra Krunic 6-3, 7-6 to reach the second round.

Ostapenko, who was once ranked No 5 but has slid to No 77 after a major loss of form, will need to rediscover that Roland Garros winning game when she takes on American Alison Riske, who will aim to take out another Paris champion following her 2-6, 6-1, 6-3 first round win over 24th seed Garbine Muguruza.

Petra Kvitova delivered a devastating display of power-hitting to thrash qualifier and fellow Czech Denisa Allertova 6-2, 6-4.

Kvitova, twice a quarter-finalist at Flushing Meadows, has been recovering from injury in recent weeks, but there appeared few signs of her arm troubles. The No 6 seed will face Andrea Petkovic in the second round after the German defeated Romania's Mihaela Buzarnescu 6-3, 6-4.

Seventh seed Kiki Bertens also faced little resistence in her opening assignment after the Dutch seventh seed beat lucky loser from Spain Paula Badosa 6-4, 6-2.

In the men's draw, Italy's Matteo Berrettini eliminated veteran Frenchman Richard Gasquet 6-4, 6-3, 2-6, 6-2, while Australian 20-year-old Alexei Popyrin had too much for Argentina's Federico Delbonis in a 6-1, 7-5, 7-6 win.

Italian Lorenzo Sonego was also a comfortable winner, defeating Spain's Marcel Granollers 6-3, 6-4, 6-4.