Aryna Sabalenka took a big step towards retaining her Australian Open crown by beating American fourth seed Coco Gauff 7-6 (2) 6-4 in a thriller on Thursday.
The Belarusian will meet Zheng Qinwen or qualifier Dayana Yastremska in the final.
In a rematch of their US Open title clash in September, Sabalenka and Gauff made contrasting starts as Sabalenka fired an ace and revved up her forehand to hold before pouncing on two double faults by Gauff to break.
Gauff hit back right away and the pair swapped breaks again but the 19-year-old New York champion continued to teeter on her serve, allowing Sabalenka to settle her nerves after going 6-5 down in a frantic spell to clinch the first set in a tiebreak.
The pair were locked together until 4-4 in the second set as Sabalenka countered Gauff's speed with power and the 25-year-old second seed edged ahead with a decisive break when the teenager hit a shot long before sealing victory with two massive serves.
Sabalenka will set her sights on becoming the first woman to win consecutive Australian Open titles since compatriot Victoria Azarenka in 2012 and 2013.
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