Osaka returned to Rod Laver Arena for the first time since winning the Australian title last February. It was her first tour-level match since a third-round loss to Leylah Fernandez at the US Open in September.
Osaka was up a set and a break before Cornet went on a five-game roll to force the match into a third set. The former No. 1-ranked Osaka got just over 38% of her first serves into play, had eight double-faults and 57 unforced errors, but countered that with 51 winners. She faced only three break points in a match that lasted just over two hours.
“I feel like I made a lot of unforced errors today,” top-seeded Osaka said. “But I expected that because it is the first match and I was really nervous.”
Travel restrictions during the COVID-19 pandemic mean there’s a crammed schedule of events Down Under before the Australian Open starts Jan. 17.
There are three events being played this week in Melbourne as part of Tennis Australia’s Summer Set of tournaments — two WTA tournaments and one ATP. In Adelaide, there is a joint ATP and WTA tournament this week. The ATP Cup is being played in Sydney.
Pegula, who reached the quarterfinals at last year’s Australian Open, led 5-3 and had set points before Begu rallied for victory.
In earlier matches, American teenager Coco Gauff beat Ulrikke Eikeri of Norway 6-2, 6-1 to set up a second-round match against top-ranked Ash Barty, 2020 Australian Open champion Sofia Kenin beat Lucia Bronzetti 7-5, 7-5, and Anastasia Gasanova beat eighth-seeded Elina Svitolina 5-7, 6-4, 6-3 in a match lasting 2 hours and 34 minutes.