RNZ reports the world number two and top seed lost to Brengle, who is ranked 72 in the world, 4-6 7-6 4-6 in a see-saw second-round contest.
The final blow came as a double fault on a match point.
At a post-match news conference, Williams said the swirling wind had been a major factor for her.
"I really think I played - I'm trying to think of a word that's not 'obscene', but that's pretty much how I played. Eighty-eight unforced errors is too much ... just way too many unforced errors.
