Koepka pleased to see reward for 'countless hours' of hard work

The American made a dream start to his title defence in Memphis, matching a career-low with an eight-under 62 in the first round to hold a two-stroke lead.

Koepka, who had missed cuts in two of his previous three tournaments, said his performance was thanks to the work he had put in.

"It's all what's gone on behind the scenes," the four-time major champion told a news conference.

"I do feel comfortable at this place, I like it, but at the same time, it's the first time I feel like I know where my misses are, I know when the club's in the correct spot, I know when the putting stroke's nice.

"It's all just the work we've put in over the last three weeks of countless hours of beating balls and on the putting green."

Looking to go back-to-back.@BKoepka has made a habit of defending titles.He leads by two at the @WGCFedEx. pic.twitter.com/vnYWgedRkh

— PGA TOUR (@PGATOUR) July 31, 2020

Koepka has one top-10 finish in 10 starts this year, but the world number six was happy with his improvement on Thursday.

"I played good, I drove it well, putted well, chipped it well, did everything very solid, missed in the correct spots," he said.