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The American wrapped up a 7-6 (7-5) 6-1 victory and will now face top seed Barty, who will still be smarting from her surprise quarter-final exit at the Australian Open.
Barty is the reigning champion in Adelaide and will be seeking to put that loss to Karolina Muchova firmly behind her.
Collins' compatriot Shelby Rogers also prevailed, beating Veronika Kudermetova 6-3 7-6 (7-4) to set up a clash with third seed Johanna Konta.
Anastasija Sevastova overcame Caroline Garcia 6-2 6-4, while eighth seed Wang Qiang was a 6-4 6-3 winner over teenager Olivia Gadecki.