They both had chances to grab a break in set number two but the result followed the serve until 3-3 when Bary netted a forehand to give the serve away, pulling it back in the very next game with a half&volley victor that gave her a lot of confidence. 'The biggest thing, I believed that I could I win.
"I had nothing to lose out here so I just came out and played with freedom".
"I knew that Sim would be a little bit rusty, being her first match of the year, first match in a while".
"So I was very happy I was able to make the most of it".
The 27-year-old Halep will be at the Australian Open next week in Melbourne without a coach after parting ways with Australian mentor Darren Cahill, who can longer commit to Halep due to family reasons.
With a cool change coming through Sydney's west, wind gusting through Ken Rosewall Arena pushed some shots over a metre from their natural flight path.
"In those conditions, it's very tricky court level".
Down in the first set, Barty recovered with a vengeance, aided by her excellent return game and backhand slice.
"I. was able to serve my way out of it and get forehands and give myself an opportunity".
Her play improved from there.
But Barty was undaunted, using her signature court craft to break straight back and secure victory two games later. "It feels like a big, big, big difference".
Halep won their previous two meetings last summer but she wasn't a clear favorite today, struggling with a back injury for months and not winning a match since Cincinnati back in August when she won the title.
"I certainly fear no one and I feel like I can go out there and match it with the world's best", Barty said.
It is Putintseva's sixth career Top 10 victory, second Top 5 win following her defeat of Dominika Cibulkova en route to the 2017 St Petersburg final and second consecutive win over Stephens following an equally dramatic 5-7, 6-4, 7-6 (3) triumph in the first round of Nurnberg past year.
She narrowly escaped defeat in the first round, and slumped out to Kazak qualifier Yulia Putintseva 3-6, 7-6 (7/4), 6-0, meekly surrendering in the final set.
In other second-round matches, top-seeded Stefanos Tsitsipas defeated Guido Andreozzi 6-3, 6-4, third-seeded Diego Schwartzman beat qualifier Guillermo Garcia-Lopez 6-2, 6-3, Yoshihito Nishioka defeated Andrey Rublev 6-3, 6-1 and No. 8 Andreas Seppi beat Martin Klizan 7-6 (2), 6-2.
"Obviously it's disappointing, but the sun will come up tomorrow".