Day shot a massive six shot win to notch up his fourth victory in his standout American season.
His scores of 68-68-63-62 took him to a tournament low of 19-under, well ahead of second placed Swedish pro Henrick Stenson.
The highlight of Day’s victory was his impeccable putting, with a combined 41 metres of successful sinking, including a ten metre bomb on the 15th hole.
Day celebrates his win in front of an adoring crowd.
Day’s form is especially impressive considering that in his first 154 PGA Tour starts he had two wins and now in his last 14 he he's notched up four.
Following the triumph, Day said his form was far from finishing.
“I’m just trying to improve each week, but it’s been a special summer for me, and it’s not over,” Day said.
“To be able to play the way I did over the weekend here was fantastic.”
With three rounds remaining and leading Jordan Spieth, Day is now in the drivers seat to become the first Australian to win the Fedex Cup playoff series as well as its US$10 million bonus.