World number one Halep stunned in Sydney

Prior to her Sydney International win Barty had failed to take a set off Halep in two previous attempts

Prior to her Sydney International win Barty had failed to take a set off Halep in two previous attempts

Ash Barty has earned one of the biggest wins of her career with a 6-4 6-4 victory over world number one Simona Halep in the second round of the Sydney International. 'The biggest thing, I believed that I could I win. "In extremely tricky conditions, [I was] very happy with the way I was able to keep it kind of together".

In first-round matches, 10th-seeded Elise Mertens beat qualifier Katerina Siniakova 7-6 (4), 2-6, 6-2 and Anett Kontaveit defeated Monica Puig 2-6, 7-5, 6-1.

Halep had the first break of serve in the second set and even served to make it 5-3 but Barty rattled off successive breaks to take the set 6-4 and complete a straight-set win over the French Open victor.

Barty was made to work for the victory, with Halep going up a break in the second set.

She had already accounted for another French Open victor, Jelena Ostapenko, in the opening round and had an extra gear against Halep, breaking serve twice to win the first set. Just very happy I was able to come out and execute.' 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.

"It was extremely hard conditions, very swirly down at court level".

"She played really well".

Barty, ranked 15 in the world, surged into the quarter-finals in Sydney with a 6-4, 6-4 triumph over the reigning French Open champion and 2018 Australian Open runner-up.

Fourth seed Stephens was beaten by Johanna Konta in the first round of the Brisbane International last week, and the American had to recover from a first-set bagel to defeat qualifier Ekaterina Alexandrova in the opening round in Sydney.

Earlier on Wednesday, Samantha Stosur was knocked out in a two-sets-to-one loss to Switzerland's Timea Bacsinszky. He will next face Japanese qualifier Yoshihito Nishioka.

Veteran Italian Andreas Seppi is also through to meet top seed Stefanos Tsitsipas of Greece, while fifth seeded Alex De Minaur set up an all-Australian last eight tie with Jordan Thompson. France's Gilles Simon will take on another Australian, John Millman.