Caroline Wozniacki said she was "proud" to have booked her place in the semi-finals of the Australian Open after battling past Carla Suarez Navarro.
The second seed looked well placed to cruise into the last four when she stormed through the first set, but her Spanish opponent rallied to level via a tie-break.
However, Wozniacki changed her tactics in the decider and the ploy worked as she eventually ran out the 6-0 6-7(3) 6-2 winner.
It's going to be a tough one but I'm excited for it.Caroline Wozniacki
The Dane is through to the last four in Melbourne for the first time since 2011 and will now meet Belgium's Elise Mertens, following her shock 6-4 6-0 victory over fourth seed Elina Svitolina.
Mertens is in fine form having recently defended her Hobart International title and with her yet to drop a set Down Under, is 1212/1 to win the tournament outright.
It looks set to be a titanic tussle and Wozniacki, who is 11/10 for the tournament outright, will certainly be battle-hardened by Tuesday's win.
The 27-year-old admits she was made to work hard against Suarez Navarro and is looking forward to another tough test against the unseeded Belgian.
"I knew it wasn't going to be that easy ... In the second set I had the chance to close it out so I was disappointed I didn't do that," Wozniacki said on-court. "I'm just proud that I managed to stay cool and finish it off in the third set."
She added: "(Mertens) has had an amazing start to the year. It's going to be a tough one but I'm excited for it."
Wozniacki is 4/9 to win on Thursday, while Mertens is available at 7/4.
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