AUGUSTA, United States (AFP) - Big-hitting American Dustin Johnson made Masters history in Friday's second round by bagging three eagles at Augusta National.

He birdied the other par-5 hole to make it seven-under for the course's four longest holes en route to a round of four-under par 68 that left him sharing third place, seven strokes off the lead held by Jordan Spieth.

Johnson's eagles came at the second, after he had double-bogeyed the opener, the eighth and the 15th, with the birdie at the 13th.

The first player to hit three eagles in Masters history, self-effacing Johnson took it all in stride as no big deal.

After all, he already had in his office four of the crystal goblets that Augusta National awards to eagle baggers, meaning he now owns a total of seven.

"It wasn't like I was hitting it any farther. It was normal shots that I've had in the past," he said.

It had been, he added, "an up-and-down" kind of day.

Johnson arrived as one of the favourites for the green jacket after hitting a rich vein of form this season that included four top-10 finishes with a win in the WGC-Cadillac tournament.

It was all in stark contrast to a troubled last year when the South Carolinian needed to take six months off from the game to deal with unspecified "personal issues". He says is over those problems now and has become a family man with the birth of his first child, a son, with Pauline Gretzky, the daughter of the hockey legend.

Johnson has come close to winning a major before, notably at the 2011 British Open and the 2013 PGA Championship, when he fell foul of an obscure ruling involving grounding the club in sandy areas.

But despite believing that Augusta National suits his game, he has struggled to post a challenge in the Masters, with a tie for 13th his best finish in five previous appearances.

"I always feel good at Augusta. I think the golf course sets up well for me. I just never really played that well here," he said.

"But coming in this year, I felt really confident in my game. I've been playing really good golf and I'm continuing to play good golf.

"I haven't played my best golf the last two days, but I've played pretty good. Hopefully it's just going to keep getting better.

"Just need to go out and play two good, solid rounds. Tomorrow is an important day. Just need to play another good, solid round and put myself in a position to have a chance to win on Sunday."