Australian Jason Day clinched his first PGA Tour victory in over five years on Sunday, winning the Byron Nelson tournament with a nine-under-part 62 at TPC Craig Ranch in McKinney, Texas.

The 35-year-old had not won since the Wells Fargo Championship in May of 2018 but his birdie on the par-5final hole earned him a one stroke win over South Korea's Kim Si-woo and American Austin Eckroat.

Day's first ever win on the PGA Tour had come in the same tournament 13 years ago, albeit at a different venue in suburban Dallas.

"It's been a struggling few years, five years since our last win. The way I played today was really special. I'm very pleased and happy with how things have progressed over the last couple of years. 1,835 days to be exact," he said.

Day said battling against a back injury had hampered his form but that his determination had helped him get back to his best.

"Just non-stop grinding and non-stop wanting to improve and to try and get better. A lot of injuries with my back... just trying to get through those three years, just trying to get through a tournament was difficult," he said.

"So, to be on the other side of it, to be healthy...really winning again. It's so good to be on the other side," he said.

Day found his momentum with three straight bridies from the third hole onwards and the highlight of his round was chipping in from 37 feet for a birdie on the par-4 12th.

With Kim having taken a share of the lead, one hole in front of him, with a birdie on the 18th, Day knew that a par would only be enough for a playoff with the Korean.

The Australian rose to the challenge with a superb 80-yard approach shot on the final hole landing two feet from the hole for a simple birdie and the win.

Eckroat, in the final group, was left needing an eagle to force a playoff with Day, but his approach went over the back of the green and he had to settle for birdie and a round of 65.

"Everything was solid, and I really felt like I played well enough to win. It's just hard to beat a guy that goes out and shoots 9-under," said the 24-year-old.

After his disappointing third round 71, world number two Scottie Scheffler had threatened, reaching the turn with four birdies, but he had to settle for a share of fifth place after missing a simple birdie putt on the last.

Scheffler will now turn his thoughts to the PGA Championship at Oak Hill next week.

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