(Photo credit: David Kirouac-Imagn Images)

For the first time in her career, Madison Keys walked out onto a Grand Slam stage on Tuesday as the tournament's defending champion.

For the No. 9 seed, the first hour and 12 minutes against Ukraine's Oleksandra Oliynykova represented a major reality check. After a slow start, Keys cruised in the final 30 minutes and beat Oliynykova 7-6 (6), 6-1 in the first round of the Australian Open in Melbourne.

Keys could not solve the unorthodox tactics of her opponent in the early going, quickly reached double figures in unforced errors and found herself trailing 4-0. The American bounced back to win four consecutive games but trailed 6-4 in the first-set tiebreaker. Keys came through with four consecutive winners, either set up by or finished with her trademark forehand groundstrokes.

Keys made 30 unforced errors in the first set. She carved that figure to seven and only lost 12 points in the second set to advance to the second round, where she will face American Ashlyn Krueger.

'I was actually talking to Lindsey Davenport yesterday and she reminded me that not many people get to be a defending champion at a Grand Slam,' Keys said after the match. 'So just trying to enjoy it and embrace it. And as nervous as I was at the start, I'm really glad to be back and that I got through that match.'

Krueger defeated Sara Bejlek from Czechia 6-3, 6-3.

A pair of seeded players fell in the sunny and breezy afternoon conditions in Melbourne. No. 22 Canadian Leylah Fernandez lost to Indonesian Janice Tjen 6-2, 7-6 (1), while No. 30 Australian Maya Joint dropped a 6-4, 6-4 decision to Czech Tereza Valentova.

The news was not all bad for the host nation, as 20-year-old Australian wild card Taylah Preston defeated veteran Shuai Zhang of China 6-3, 2-6, 6-3.

Five other seeded players advanced, led by No. 5 Elena Rybakina of Kazakhstan with a 6-4, 6-3 defeat of Slovenia's Kaja Juvan and No. 10 Belinda Bencic of Switzerland with a 6-0, 7-5 win against Britain's Katie Boulter.

Bencic takes a career-best 12-match winning streak into her second-round clash with Czech teen Nikola Bartunkova, a 7-6 (7), 0-6, 6-3 winner against Australia's Daria Kasatkina.

'I think I was very focused, very ready,' Bencic said. 'I was also ready for it to become a little bit more tight. Of course, sometimes it's not easy to win the first set 6-0.'

Two-time Australian Open champion Naomi Osaka, the No. 16 seed from Japan, opened with a 6-3, 3-6, 6-4 victory against Croatia's Antonia Ruzic.

No. 24 Jelena Ostapenko of Latvia ousted Slovakia's Rebecca Sramkova 6-4, 6-4, and No. 31 Anna Kalinskaya of Russia took down Britain's Sonay Kartal 7-6 (3), 6-1.

Germany's Laura Siegemund rallied for an 0-6, 7-5, 6-4 upset of 18th-seeded Russian Liudmila Samsonova.

Other winners included former No. 1 Karolina Pliskova of Czechia and her countrywomen Katerina Siniakova and Linda Fruhvirtova. China's Xinyu Wang, Australia's Maddison Inglis, Romania's Sorana Cirstea, Austria's Julia Grabher and France's Varvara Gracheva also moved into the second round.

--Field Level Media