The Sydney talent was stuck in last year's northern beaches lockdown before enduring more restrictions when allowed into Victoria ahead of this week's Great Ocean Road Open.

It took a set to dust off any cobwebs in Monday's first round, but the world No.121 held his nerve to beat Germany's Dominik Koepfer 5-7 6-4 6-1 and set up a second-round meeting with world No.45 Alexander Bublik.

He was one of six local male victors on Monday, with Jason Kubler, Aleksandar Vukic, Max Purcell and Alex Bolt, who beat Thanasi Kokkinakis, also through to the second round.

Harry Bourchier was the final Australian through, making the most of his late call-up because of Bernard Tomic's withdrawal to beat compatriot Marc Polmans 6-4 6-4 on Margaret Court Arena.

O'Connell stormed up the rankings in 2019, winning more matches than anyone on tour, before notching his maiden major tournament victory at last year's US Open.

He was stopped by then-third seed Daniil Medvedev in the second round but showed he was ready to make noise again after earning a wildcard into the Australian Open from February 8.

"It hasn't been the ideal preparation, but regardless I've still had a pre-season even though it's been a bit all over the place," he said.

"It was super fun to be back out there on court.

"I had to stay calm, back myself and I knew things would turn eventually my way and that's what happened."

O'Connell has a legitimate eye on a top 100 spot that would earn him automatic entry into the world's grand slams.

But he has company in good mate Vukic, who opted to take the American college route to professional tennis and, after qualifying for the French Open last year, franked his form with a 6-4 7-5 defeat of Yen-Hsun Lu.

He will play Italian young gun Jannik Sinner next, while wildcard Purcell - a doubles finalist at the Australian Open last year - will play Russian second seed Karen Khachanov after beating Norbert Gombos 6-4 6-4.

Left-hander Bolt had no answer to an on-song Kokkinakis in the first set but, like O'Connell, was able to weather the storm to win 2-6 6-4 6-3 as mistakes crept into his fellow South Australian's game.

Kubler was just as impressive, rallying from a set down to beat ninth seed Lorenzo Sonego 3-6 6-3 6-3.

Highly rated as a junior, Kubler has suffered his share of injury pain and rated the victory the second best of his career and a "little pat on the back".

American Frances Tiafoe, an Australian Open quarter-finalist two years ago, was felled by France's Corentin Moutet 3-6 6-4 6-4 in the biggest upset of the day.

Australian Associated Press