The 19-year-old became the first Australian woman since Jane Flemming in 1994 to win the heptathlon and 100m hurdles.

After Sally Pearson's late withdrawal from the hurdles final, threw the race wide open with Mucci being the one to take gold in the final with a time of 13.09.

The personal best time also broke a 27-year-old record for the quickest 100m hurdles run by an athlete under the age of 20 and the eighth fastest in Australian history.

“I really wanted to be fresh for this race, but knowing I wasn’t going to be, I had to dig deep to find some adrenaline,” Mucci said.

The teenager admitted that she had been suffering from the heptathlon on Thursday and Friday. 

“I was feeling alright yesterday on my rest day, and then this morning I woke up sore,” Mucci said.

“I just had to run on a lot of adrenaline in the heat and manage a quick turnaround for the final.”

The result came after winning the heptathlon just two days earlier with a score of 5844 points.