Madison Keys began her Australian Open title defence with a nervy 7-6(6) 6-1 victory over Ukraine’s Oleksandra Oliynykova on Tuesday, while fellow American Ben Shelton defeated Ugo Humbert in a battle of lefthanders to reach the second round.

Long queues formed outside Melbourne Park for a third straight morning with many keen to watch Jannik Sinner, who faces Hugo Gaston in his first hurdle towards winning a third straight title at the year’s opening Grand Slam.

A year on from her triumph on the blue courts Down Under, Keys was in all kinds of trouble early on at Rod Laver Arena in her opener against Oliynykova, who was appearing at a Grand Slam for the first time.

A double break down thanks to some untimely double faults, Keys trailed 4-0 before fighting back, drawing level at 4-4, but the American was dragged into a tiebreak where the unorthodox Oliynykova caused chaos with her deep, looping shots.

Oliynykova brought up two set points but Keys erased the deficit with some trademark big-hitting to eventually snatch a tense tiebreak, punctuating her escape with a roar.

The second set was much more routine as Keys closed out the victory to set up a second-round match against compatriot Ashlyn Krueger.

“It was incredible to walk out for the first time since walking off of the court a year ago,” a relieved Keys said.

“Obviously I was very nervous at the start but I’m just so happy to be back and playing here.

“I spoke to Lindsay Davenport the other day and she reminded me that not many people get to go out there and defend a Grand Slam. So I’m just trying to embrace it and enjoy it. As nervous as I was at the start, I’m glad I got through that match.”

The was more success for the ‘Stars and Stripes’ when eighth seed Shelton, who lost to Sinner in last year’s semi-finals, battled to a 6-3 7-6(2) 7-6(5) win over Humbert.

Fellow American Ethan Quinn also reached the second round with a 6-2 6-3 6-2 win over 23rd seed Tallon Griekspoor.

Italians advance

Wildcard Taylah Preston gave home fans something to cheer by beating China’s Zhang Shuai 6-3 2-6 6-3 for her first Grand Slam match win but Maya Joint was unable to join her in the second round, Australia’s number one losing 6-4 6-4 to Tereza Valentova.

Former US Open runner-up Leylah Fernandez also exited after the 22nd seed lost 6-2 7-6(1) to Janice Tjen, who became the first Indonesian to win a match at the Australian Open in 28 years.

Lorenzo Musetti advanced after Raphael Collignon retired while trailing 4-6 7-6(3) 7-5 3-2, the fifth seed’s win setting up an all-Italian match-up with Lorenzo Sonego.

Luciano Darderi beat Cristian Garin 7-6(5) 7-5 7-6(3) but did not stick around long to celebrate, the Italian 22nd seed sprinting to the toilet after shaking his opponent’s hand.

World number two Sinner plays Gaston in the evening session, before twice Australian Open champion Naomi Osaka closes play on the main showcourt against Antonia Ruzic.