The London relay gold medallist beat her previous personal best of 52.33 seconds to claim the first individual world record by an Australian since the supersuit period.
"It happened when I least expected it. I still can't believe it happened," Campbell was quoted as saying in the Australian Associated Press.
"People have been asking me when am I going to break a world record for the last three years.
"Now they will stop asking me the question."
After a few testing years with injury and illness, the world number one has her eyes firmly set on the gold at the Aug. 5-21 Rio Games.
"Anyone who goes to the Olympics and says they are not after gold are kidding themselves," she added.
(Reporting by Nivedita Shankar in Bengaluru; Editing by Amlan Chakraborty)
