In her opening round match, just four games in, the world number three and five-times Australian Open winner tumbled to the court after twisting her right ankle.
Williams required urgent running assistance from medical staff.
She was leading 4-0 over her little-known Romanian opponent Edina Gallovits-Hall.
A hushed silence fell over the crowd at Hisense Arena, as the popular American was given lengthy treatment by her medical team.
But, the grand slam queen later returned to the court and played on largely untroubled, though slightly restricted, romping to a brutal 6-0 6-0 victory.
The superstar then headed straight for the changerooms, even refusing the customary on-court interview.
Williams' ankle had already been heavily strapped to begin the match. The existing strapping was cut away, before new bandages were applied to reinforce the delicate joint.
Williams is in the same side of the draw as defending champion Victoria Azarenka.
Azarenka also triumphed on the second day's play in Melbourne, dispatching her Romanian opponent Monica Niculescu in straight sets, 6-1 6-4.