Brooks Koepka revealed he battled illness on his way to the WGC-FedEx St. Jude Invitational title.

The world number one fired a five-under 65 in the final round on Sunday to claim a three-stroke victory and his first WGC crown.

However, Koepka, who now has seven PGA Tour wins, said he had been unwell throughout the tournament.

"It doesn't affect me hitting a golf ball. I don't feel good," he told the Golf Channel.

"I haven't felt good all week, but I don't want to make an excuse, I'm not trying to complain. Just get on with it. People go to work sick all the time."

Koepka's win continued what has been a dominant run by the American, who has secured four major triumphs since the start of 2017.

The 29-year-old said his win at TPC Southwind in Memphis, Tennessee, was among his favourites.

"It's special. These last few years have been unbelievable, it's been an incredible run, I'm playing some good golf and I'm excited for what the future holds," Koepka said.

"This place has always been special to me, everything, with FedEx being here, St. Jude being here, it's always been a fun place for me to come.

"It's always a special place, but to win here, this one goes down as one of my favourites."

Brooks Koepka saw off Rory McIlroy to claim his maiden World Golf Championship at the WGC-FedEx St. Jude Invitational.

World number one Koepka celebrated a three-stroke victory after carding a five-under-par 65 in Memphis on Sunday.

Koepka – a four-time major champion – enjoyed a flawless final round with five birdies, including three in a four-hole stretch at TPC Southwind.

The American star and FedEx Cup leader finished 16 under overall for his third win of the season and seventh of his career, ahead of countryman Webb Simpson (64).

Simpson's round was highlighted with an eagle on the par-five third hole but a bogey just before making the turn sullied his scorecard.

Australian Marc Leishman, who also climbed up the leaderboard, rounded out the top three at 12 under after his final-round 67.

Overnight leader and former world number one McIlroy ended the tournament five shots off the pace following his one-over-par 71.

McIlroy – who won the tournament in 2014 – was the man to beat following the third round after he posted an eight-under-par 62 for a one-shot lead ahead of Koepka.

But the 54-hole leader was unable to maintain his charge after missing the cut at The Open last week – McIlroy falling victim to two bogeys on his back nine as he finished alongside Tommy Fleetwood (66) and Matthew Fitzpatrick (69).

Spanish star Jon Rahm (69) was a stroke further back at 10 under, ahead of Ian Poulter (69).

Defending champion Justin Thomas had to settle for a share of 12th position at six under following his final-round 71.

Thomas finished alongside Jordan Spieth (68), Alex Noren (73), Patrick Reed (68), Rafa Cabrera Bello (66), Aaron Rai (67), Patrick Cantlay (68) and Cameron Smith (68).

Meanwhile, Dustin Johnson – the 2016 champion – ended the event a stroke further back after shooting a two-under-par 68.

Rory McIlroy and Brooks Koepka are excited for what shapes as being an enthralling final-round battle at the WGC-FedEx St. Jude Invitational.

McIlroy fired an eight-under 62 at TPC Southwind on Saturday to grab a one-stroke lead over world number one Koepka.

The duo played together during the opening two rounds and they will be the final pairing on Sunday, something they are both looking forward to.

"It is exciting. Brooks is the number one player in the world, four majors in the last three years," McIlroy said.

"He's the man right now. I got to play with him the first couple days and I enjoyed it. I enjoyed seeing what he can do."

McIlroy tops a star-studded leaderboard ahead of Koepka after missing the cut at The Open, where the American finished tied for fourth.

Koepka believes McIlroy, who has two wins this year, will be hard to stop in the final round.

"It will be fun. Rory's playing some good golf, especially with the start he got off to," he said.

"Played with him the first two days. The way he struck it was really impressive. He's putting well and you know he's going to be tough to beat."

Rory McIlroy fired an impressive eight-under 62 to move into a one-shot lead at the WGC-FedEx St. Jude Invitational on Saturday.

McIlroy, who missed the cut at The Open, holed nine birdies and just one bogey during his third round at TPC Southwind, moving into 12 under and top of a leaderboard featuring many contending stars.

The Northern Irishman made five birdies on the front nine, including three straight beginning at the seventh in Memphis, Tennessee.

McIlroy had a slight setback on the par-four 12th but recovered well with four more birdies on his last five holes, including a successful 27-foot birdie putt on 18 to take the outright lead.

However, if McIlroy wants his third win of the year he will have to hold off a surging field trailing closely behind him.

Brooks Koepka moved into second place at 11 under and 36-hole leader Matt Fitzpatrick is a shot further back.

Marc Leishman (63), Alex Noren (66) and Jon Rahm (68) are tied for fourth at nine under, a shot ahead of Ian Poulter (67), Thorbjorn Olesen (65) and Billy Horschel (69).

Leishman produced a chip in off the green for an eagle at the par-five 16th hole.

Justin Thomas (66) and Tommy Fleetwood (65) climbed up the leaderboard to join Webb Simpson (68) and Bubba Watson (68) in a tie for 10th place at seven under.

Meanwhile, Dustin Johnson was again unable to get going, shooting a third straight one-under 69 to be tied for 26th.

Jon Rahm revealed he felt "dead" in the lead up to the WGC-FedEx St. Jude Invitational before opening with an impressive eight-under 62.

The Spaniard opened up a three-stroke lead after the first round at TPC Southwind in Memphis, Tennessee on Thursday.

But Rahm, searching for his first WGC win, said he was exhausted ahead of the tournament, leaving him playing the front nine at the course for the first time during the opening round.

"I can tell you getting to the first tee today [Thursday] was the first time I stepped on that nine," he said.

"I didn't see my back nine today at all before today. I didn't do anything Monday or Tuesday, I just rested and stretched at the hotel.

"Yesterday I came with the plan of playing 18 holes. I putted and warmed up, and after four holes, I teed off on 10, I think that was when I got to 14 or 15, I was dead. I couldn't swing properly. I was really tired, so I just decided to finish the round of nine holes, eat and just putt a little bit and go."

Despite the unusual preparation, Rahm holed eight birdies in his first round, including five from holes one to eight – his back nine.

The 24-year-old said the way he set himself up led to his superb start as he took a three-shot lead over Patrick Cantlay, Bubba Watson, Cameron Smith, Hideki Matsuyama and Shugo Imahira.

"The key to all those birdies, my position on the greens was really good," Rahm said.

"I was able to not really go at the pins every single time, but I was able to make myself putts that for the most part I felt with very little break ... if I could do that every day of the year, that would be amazing."

Jon Rahm used a brilliant opening round to grab a three-stroke lead at the WGC-FedEx St. Jude Invitational on Thursday.

Rahm, who is fresh off a tied for 11th finish at The Open, shot an eight-under 62 with five of his eight birdies coming on his back nine at TPC Southwind.

What was more impressive was his putting as Rahm missed just one putt inside 25 feet during the first round in Memphis, Tennessee. He was a perfect five for five from 15-20 feet.

The Spaniard, still looking for his first WGC win, tied the low round of his PGA Tour career.

But, he has a star-studded field behind him.

There is a five-way tie for second place at five under, with Hideki Matsuyama and Bubba Watson joined by Patrick Cantlay, Cameron Smith and Shugo Imahira.

Watson's round featured a birdie on his final hole after bogeys on the par-four 10th and 13th holes.

Behind them is a sizable group of Ian Poulter, Thorbjorn Olesen and Tyrrell Hatton, among others, a shot further back.

Justin Rose, Bryson DeChambeau and Billy Horschel are in a five-way tie for 13th at three under and in good position to move up the leaderboard on Friday.

Jordan Spieth nearly joined the top of the leaderboard after five birdies and just one bogey through 11 holes.

But the American then carded two triple bogeys, making seven at the 12th and 15th holes before finishing with an even-par 70.

World number one Brooks Koepka made a fine start with a 68, while Rory McIlroy and Dustin Johnson opened with 69s.

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