Barty became the first Australian to win the event since Chris O'Neil captured the women's title in 1978.

O'Neil was present in the stands cheering as the crowd on the flooodlit Rod Laver Arena erupted when Barty converted her first match point with a forehand crosscourt winner.

Collins was the first to set up a break point in the contest with some forceful grounstrokes but a calm and composed Barty found the range with her serve to get out of trouble. She then broke in the next game when her opponent served up a double fault.

Some uncharacteristic forehand errors from Barty allowed Collins, who will make her top-10 debut when the rankings are updated on Monday, to break early in the second set and the American let out a shriek of "Come On" to celebrate opening up a 3-0 lead.

The American broke Barty's delivery, which looked almost impregnable this past fortnight, a second time in the set. But when Collins appeared to be on the verge of levelling the match as she served at 5-1, the Australian showed nerves of steel and raised her game.

Barty got the set back on serve and then dominated the tiebreak to complete a memorable comeback that left the home nation rejoicing all over Australia.