American Mitchell – the world number 162 – bogeyed the opening two holes in the final round Honda Classic, last leaderboard-9 K Mitchell (US); -8 B Koepka (USA), R Fowler (USA); -7 R Palmer (USA), L Glover (USA); -6 V Singh (Fiji) Full standings
Keith Mitchell moved a 15 meter long birdie putt on the 18th to win his first PGA Tour title at the Honda Classic.
Mitchell finished nine under-one shot ahead of Brooks Koepka and Rickie Fowler – at PGA National in Florida.
Mitchell, 27, was bound after the first two rounds and fourth Sunday four of the last seven holes for his first victory as a pro
"My mind started to wander a bit at the end and then I hit a good putt, "he said.
"It does not even come close to sinking in. Do not expect it, I do not want it, this is just great Playing like I did was incredible."
Vijay Singh missed the chance to create history after a closing round of 70 left him in sixth place.
The 56-year old Fijian had tried to become the oldest winner of the PGA Tour and surpassed the record of 52-year-old Sam Snead in 1965.