Brooks Koepka stormed into the lead at the Masters on Friday and then warned his rivals that he is back in the form that saw him win four major titles and rise to the top of the sport.

Koepka looked confident and in control as he marched to a five-under par 67 at Augusta National to follow up his opening round 65 and lead the field.

With a large crowd following him up to the 18th hole, where he was warmly applauded after narrowly missing a birdie putt, it certainly felt like the old Koepka was back.

"I feel really good," he said. "I like the way I'm swinging the golf club, putting it, chipping it, driving it, iron play is solid. It feels really similar."

The 32-year-old Floridian won his two US Open and pair of PGA Championship titles in a two-year spell between 2017 and 2019 during which he became the world number one.

A series of injuries and a knee surgery in March 2021 saw Koepka's form slump and he missed the cut at the past two Masters.

Last year, he also missed the cut at the British Open and finished in 55th place at both the PGA Championship and US Open.

The second round was suspended on Friday afternoon due to the threat of electrical storms, with Koepka's nearest challenger, US amateur Sam Bennett, having finished four strokes behind him.

Play resumed 21 minutes later. (AFP)