Ill winds gusted across Augusta National, the breezy conditions playing havoc with the world’s most skilled shotmakers, who largely scrambled to contain the damage.

“I’m really happy with the round and how I grinded and battled out there,” McIlroy said. “And I’m going to have to do that again tomorrow because it’s going to be windy out there again.”

Spieth struggled to a two-over 74, bogeys at the par-3 16th and 17th stripping a lead that had once been five shots to one with the 22-year-old American on four-under 140.

“It was a mental test. It was a battle,” Spieth said. “Still leading. Can’t complain about that.”

Spieth is trying to join Tiger Woods, Jack Nicklaus and Nick Faldo as the only players to win the Masters two years in a row.

“It’s almost a different tournament now,” Spieth said. “Tomorrow is going to be more difficult given the same winds and crustier greens.”

Four-time major champion McIlroy shot 71, with birdies at the par-5 13th and 15th and par-3 16th charging him to 141 while rivals faded.

“It was very difficult,” McIlroy said. “It was very hard to select a club.”

McIlroy hopes to join the select list that have taken all four major titles at least once -- Woods, Nicklaus, Ben Hogan, Gary Player and Gene Sarazen.

It was the first Masters round since the third in 2007 without a round in the 60s.

But it resulted in world number two Spieth and third-ranked McIlroy – who have combined to win four of the last six majors – playing together in Saturday’s last group and sure to draw the largest crowd.

“Add a lot of excitement and buzz and atmosphere,” McIlroy said. “But at the same time, I just need to focus on myself.”

Added Spieth: “I don’t think either one of us is focused on each other. I think we’re focused on the golf course.”

US Amateur champion Bryson DeChambeau, a 22-year-old American who turns professional next week, nearly spoiled the star duo but a triple-bogey at 18 dropped him to level par overall.

“You don’t want to finish with a triple but you can’t worry about that,” DeChambeau said. “I’m looking forward to the weekend.”

Spieth would overtake Australia’s Jason Day for world number one with a Masters win if the Aussie finishes outside the top five.

“It almost feels like a US Open where you have just got to survive,” Day said of the blustery conditions. “I’m just trying to survive right now.”

South Korean-born New Zealander Danny Lee and American Scott Piercy shared third on two-under 142.

Lee, trying to become the first Kiwi to win a US event since Michael Campbell took the 2005 US Open, fired 74, closing bogey-bogey to fall back.

“I’m just happy I’ll get to play on the weekend and I’ll have a chance,” Lee said.

Piercy shot 72, unable to make a run after birdies on two of the first three holes.

“It’s just blowing so hard, the wind is playing a huge part,” Piercy said. “The greens are starting to dry out. If you get them downwind it’s hard to stop the ball.”

The only others under par after 36 holes were Japan’s Hideki Matsuyama, Denmark’s Soren Kjeldsen and American Brandt Snedeker on 143.

Four-time major winner Ernie Els, who fired the worst score ever recorded on the first hole with a nine in round one, managed a double-bogey six at the first Friday on his way to a 73.

“I felt a bit more comfortable,” Els said. “I was almost back to my normal self.”

Eight-time major champion Tom Watson played his last Masters round. The 66-year-old American fired a 78 to miss the cut and received a standing ovation as he played the final hole.

“It’s time,” Watson said. “The golf course is too big for me.”

Welshman Ian Woosnam, the 1991 Masters winner, said he would no longer play the event, the 58-year-old citing back issues.

A total of 57 players made the cut at six-over 150, Bubba Watson the last of them on the number. Among those missing out were Americans Phil Mickelson, Zach Johnson and Rickie Fowler and South Africans Els and Charl Schwartzel.