“To me, this is overwhelming,” Lucic-Baroni said. “I will never forget this day and these couple of weeks.”
Ranked just 79th, she is one of two unseeded players to reach the Australian Open women’s semifinals this year, joining CoCo Vandeweghe, a 25-year-old who will face Williams on Thursday.
Lucic-Baroni will play Williams’s sister, No. 2 Serena Williams, who beat No. 9 Johanna Konta, 6-2, 6-3, later in the day.
“I’m going to try to stay calm,” Lucic-Baroni said. “I enjoyed every second out here, and I will try to do the same next time.”
Konta, a British player born in Australia, was considered a potential threat to Serena Williams because of her all-court game, athleticism and excellent recent results. (She won the Sydney tournament earlier this month.) But there are few tennis challenges that Williams enjoys more than taking on a next-generation talent for the first time on a big stage.