World No.1 Scheffler not letting up at East Lake

In a second round that brought a sense of urgency for those chasing the No.1 player in golf, Morikawa responded with nine birdies, two on the final two holes after a 93-minute storm delay, for an eight-under 63.

Schauffele finished with a pair of 12-foot putts - one for par, one for birdie, both feeling just as important as the other - for a 64.

"This course right now with how firm the greens are, it's a ball-striking type deal where you have to be in the fairways and hit your number, and he's been killing everyone at that all year," Schauffele said.

"I know he's not going to let up, so there's only one way to get him."

Morikawa has laid out a plan for the week. Still, he was seven shots back to start the day and has seen enough of Scheffler this year to know what to expect.

"He's going to continue to make birdies," Morikawa said. "He's driving it really, really well here and you're giving yourself enough wedges to make some scoring opportunities out there. For me, it's just bringing energy and just kind of staying alive out there."

They still have their work cut out for them.

Scheffler is the No.1 seed in the FedEx Cup and began the finale with a two-shot lead.

He also is playing as well as he has all year, and those immediately behind him in the FedEx Cup were not at their best in the opening round. That accounted for Scheffler having a seven-shot lead at the start of the day.

He returned from the storm delay with a pair of birdies over his final three holes and reached 21-under par. Morikawa was at 17 under and Schauffele was another shot behind.

No one else was closer than nine shots to Scheffler.

At stake for Scheffler is a chance to win the FedEx Cup and its $US25 million ($A37m) prize, which he failed to do as the top seed each of the past two years.

But he looks more comfortable on an East Lake course that has been overhauled and everyone has a big task chasing him.

Schauffele, who started the tournament two shots behind as the No.2 seed, lost ground with a 70 on the first day. He sorted out most of his swing issues and had a bogey-free day.

Scheffler tried not to get caught up in his seven-shot lead - a product of his 65 on Thursday and the next five players behind him in the FedEx Cup doing no better than 69 - though it was unusual to see a six-shot lead on the front nine on a Friday.

He went out in 32. Morikawa and Schauffele had to keep making birdies just to keep this from turning into a runaway.

Scheffler is driving it so well - he missed only three fairways - that he didn't have more than a seven-iron into a par 4 and is setting a tough target for everyone to chase.

Australian Adam Scott (67), Wyndham Clark (67) and Sahith Theegala (66) were nine shots behind.

Scott, who is tied fourth, made five birdies and had a lone bogey on the 17th.