Jabeur dipped into her box of tricks to outflank the powerful 11th seed who was slowly driven to distraction by an opponent who gave a masterclass in angles and spins.
The see-saw contest continued in a tense decider with Osaka unable to convert a break point in the fourth game only to subsequently drop her serve and slam her racquet to the ground in frustration.
Australian Open organisers announced Friday that players would compete in a biosecure "bubble" after the host city was ordered into a snap five-day lockdown, with spectators banned.