Katinka Hosszu surprised even herself after breaking a world record for a fifth time in six days, becoming the first woman in history to swim under 57 seconds in the 100m medley heats this morning in Dubai.

The Hungarian had set three new world records in the opening leg of the FINA Swimming World Cup series in Doha last Wednesday and Thursday, and smashed a fourth one in Dubai on Sunday night in the 200m medley.

In the 100m IM heats, the 25-year-old, nicknamed “Iron Lady” for her ability to swim multiple events each meet, Hosszu obliterated the field with her 56.86 seconds world record swim, which saw her improve on the mark she set in Doha last Thursday by 0.39 seconds.

“I’m so excited, I shouldn’t have gone that fast,” Hosszu said in disbelief.

“You know in track and field when they jump the high jump, you set the bar at a certain height and you can always break more records but swimming is not the same, you just have to give what you have and I’m just really excited that I went under 57 (seconds).

Tonight, Hosszu will be looking to add to the four gold medals she won on opening night of the Swimming World Cup at the Hamdan Sports Complex on Sunday.