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."