Within minutes, the 34-year-old fell to the blue hard courts, face down, and began to weep.
Eliminating fifth-seed Karolina Pliskova 6-4 3-6 6-4 to set up a clash with fellow thirtysomething Serena Williams -- a convincing 6-2 6-3 winner over Johanna Konta -- Lucic-Baroni rewrote the history books to make the semifinals at a major for the first time in a remarkable 18 years.
"Nobody in this world thought I could ever be here again, besides my closest family, my coach, brothers, sisters, my husband and mom," Lucic-Baroni told reporters. "It's fun to prove everyone wrong.
"It's more special this time for sure."
Don't be too harsh on the doubters.
When the 79th-ranked Croatian won her first-round match against China's Wang Qiang in a tight three sets, she collected a first win in Melbourne since 1998. The 19-year gap in grand slam wins -- at the same grand slam, that is -- surpassed the previous record of 17 years held by Kimiko Date at Wimbledon.
It seemed fitting that her on-court interview Wednesday was conducted by Rennae Stubbs, who Lucic-Baroni downed in 1998 prior to losing eight in a row at the Australian Open.
Back at the All England Club in 1999, Lucic-Baroni was a 17-year-old drawing comparisons to greats of the game including Steffi Graf.
Not only did she advance to the quarterfinals but Lucic-Baroni extended Graf to three sets.
But what unfolded thereafter -- rather than a career filled with trophies -- serves as a cautionary tale for seemingly can't-miss prospects.
Lucic Baroni fled to the US after she said she was abused
by her father, stopped playing for a while due to financial issues and was sued by the management company
at one time so keen to sign her, IMG. She counter sued.
Book in the works?
So much has been said and written about Lucic-Baroni that she might write a book to tell her side of the story.
"A part of it I just want to say because people assume a lot and people don't know," she said. "That irritates me when people assume things like injuries and things like that and people write about it.
"I kind of want to be known as an amazing fighter, a person who persevered against everything, against all odds. And that's what I take pride in."
Her new coach, Marin Bradaric, doesn't need to be convinced.
Bradaric saw immense potential in Lucic-Baroni, despite her age, sinking ranking -- and losing in qualifying at a warmup tournament in Sydney two weeks ago.
"In the dinner before we went to Australia I told her that I think she can win a grand slam," the 31-year-old told CNN, admitting, though, that the goal for the tournament was to simply win a round.
"Honestly I didn't expect this. Especially after Sydney.
"She took it so hard on herself, but I was still believing because I saw many good things in her game. She is improving mentally, she is trying to stay positive and believe and keep calm because sometimes she's really hard on herself, criticizing herself."
Playing with a heavily strapped left leg against Pliskova, a consequence of playing singles and doubles, a pair of medical timeouts served as major momentum shifts.
Trailing 6-4, 2-1, Pliskova called for the trainer because of what appeared to be a blister on her right foot.
At 3-3, she broke when Lucic-Baroni nervously dumped a smash into the net.
Seizing the initiative in the third set, Lucic-Baroni subsequently dropped three games in a row to trail 4-3 on serve.
That's when it was Lucic-Baroni's turn to call for the trainer. She went off court for treatment and returned a different player, winning nine points in succession and 12 of the final 13 even though she was hampered.
Lucic-Baroni upset third-seed Agnieszka Radwanska this fortnight and another grand slam finalist, Simona Halep, twice at majors. She overpowered the duo with her fierce ground strokes, shots that made her a prodigy in the first place.
But defeating Pliskova may have been more impressive.
The Czech reached last year's US Open final and won the Brisbane International earlier this month, leading more than a few to pick the 24-year-old as the Australian Open winner.
Last year's ace leader on the women's tour hit eight against Lucic-Baroni but won less than 60% of her first serve points.
"It was like her tenth match in Australia but she didn't meet an opponent who is hitting so hard and so fast," Pliskova's coach, David Kotyza, told CNN. "That broke her serve a bit. I think she thought more about the return of Mirjana, so that's why her serve went down.
"I think Mirjana was the better player. She didn't wait for the shots. She was the one who wanted to decide the points. She deserved to win."
Veterans in the semis
Lucic-Baroni, Serena Williams, 35 and Venus Williams, 36, give the semifinals a distinctly older look than usual. CoCo Vandeweghe, at 25, has bucked the trend.
Coupling Serena Williams' form and Lucic-Baroni's leg, the latter's journey -- at least on court in Melbourne -- is expected to come to an end. The last time they played was in 1998 at Wimbledon, prior to their careers going different ways.
"I remember winning," said Serena, edging ever closer to surpassing Graf's Open Era haul of majors. "I was so excited because I was so young. She was super young, too."
Lucic-Baroni vows to compete the way she says she always does.
"I'm going to go out there with my heart and do the best I can."