A surprising slide in the rankings to 28th meant former world number two Radwanska entered this week as an unseeded player, but she showed her quality in a 6-3 7-5 victory over British hope Konta.
In a repeat of last year's final match-up, this time fourth seed Konta could not take control of the contest against Poland's former Wimbledon runner-up.
Kvitova beats Britain's Konta, Barty to face Azarenka
Consolation for Konta came with the fact she completed the match without obvious physical problems, five days after being forced to retire from her Brisbane International quarter-final with Elina Svitolina due to injury.
She now heads for Melbourne and the Australian Open, where 12 months ago she reached the quarter-finals, while Radwanska stays in Sydney and faces American teenager CiCi Bellis next.
Radwanska said of her win, according to wtatennis.com: " I'm just so happy to play such a great match before the Australian Open.
"It was a top-10 level match with some ups and downs, breaks along the way. The conditions weren't easy, but I'm happy to win in two sets."
Slovakian Dominika Cibulkova won a second-round contest against Russian Elena Vesnina to reach the quarter-finals, coming through a 6-4 6-4 victor, with Czech Barbora Strycova and Australian Samantha Stosur also posting wins on Tuesday.
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