The Masters: Johnson on a roll to join Frittelli and Casey in first-round lead

Weather delays meant half of the field could not play 18 holes on Thursday, forcing several big names to return early before a swift turnaround.

World number one Johnson could carry some momentum into his second round after birdieing three of the final four holes to match Casey's seven-under 65.

Johnson carded his best round at Augusta, beating his previous low of 67 after resuming at three under through nine.

That still might not have been enough for the co-lead had Frittelli put away his birdie putt at the ninth, his final hole, for first place outright.

Dustin Johnson (T1) is looking to become the first World No. 1 to win the Masters Tournament since Tiger Woods in 2002.#theMasters

— PGA TOUR Communications (@PGATOURComms) November 13, 2020

Frittelli had missed the cut in his only previous Masters appearance but built on an impressive Thursday - which included an eagle-birdie-birdie-birdie run from the 13th - to hold an 18-hole joint-lead for the first time on the PGA Tour.

Justin Thomas was a stroke back, having not quite maintained the rampant form that took him to five under through 10 overnight.

Also in touch were a pair of veteran former champions in Bernhard Langer and Phil Mickelson, the former on four under with the latter a shot further back.

Even when the 63-year-old Langer appeared to see his round heading off the rails at the seventh, he brilliantly limited the damage to a bogey and followed up with a birdie.

It was the German's first opening round in the 60s at Augusta since 1993, when he won the second of his two titles, and he is on course to become the oldest player to make the cut in Masters history.

Oldest player to make the cut in Masters Tournament history is Tommy Aaron in 2000 (63 years, 1 month, 16 days).Bernhard Langer (T8) will be 63 years, 2 months, 18 days old on Saturday, when the second round is expected to be completed.#theMasters

— PGA TOUR Communications (@PGATOURComms) November 13, 2020

Mickelson looked to be finishing his first round on a roll until a bizarre final hole saw a great tee shot followed by a second into the bunker, then landing within four feet before missing a par putt.

Brooks Koepka could end on a high, however, as he followed favourite Bryson DeChambeau in recovering from a slow start to make 70, finishing eagle-birdie-par-birdie.

There was no such change in fortunes for a struggling Rory McIlroy.

Chasing that elusive green jacket and a clean sweep of majors, the Northern Irishman started the day at even par but saw his round quickly fall apart with bogeys at 10, 13 and 14.