Rory McIlroy
McIloy set an early clubhouse lead and watched his rivals fall apart on the back nine. Getty Images

Defending champion Jordan Spieth remains in the lead at the 80th Masters but saw his advantage almost blown away during a blustery second round at Augusta. The American led by six shots at one stage before an error-strewn back nine left him four-under after shooting 74 to allow Rory McIlroy back into contention.

The world's number two, a leader of the Masters for a sixth straight round, and three will make up the final group on the penultimate day after the Northern Irishman made 71, one of only four under-par rounds, as winds in Georgia topped 25mph. McIlroy is three-under, one shot behind the lead, and ahead of New Zealand's Danny Lee, USA's Scott Piercy and Hideki Matsuyama of Japan at the halfway stage ahead of a fascinating weekend.

"It feels great," the four-time major champion said after his round of 71 took him without touching distance of Spieth. "The course is playing difficult and the scoring is reflecting that. Once I made bogey at 11, I knew the par fives were gettable and hoped I could sneak a couple more. That's what I managed to do.

"I'm feeling a lot better after that finish - I'm in a great position going into the weekend. Jordan still has got holes to play so see what happens.

"I knew what was happening, I am a bit of a leaderboard watcher, I like to know where I stand. I wanted to be in that final group, that was my objective in the final few holes. I'm very excited. This is my best position going into the weekend at Augusta for a long time. I hope I can battle away tomorrow."

Amateur Bryson DeChambeau, playing with Spieth for the first two rounds, briefly flirted with a challenge on day two after reaching four-under for the tournament after 33 holes. However, four dropped shots in the final three holes, including a seven on the increasingly tough 18th, saw him end on level par.

The collapse of Spieth has opened the door for the host of players, with 24 players within five shots of the lead. Among them are Dustin Johnson, Troy Merritt and Daniel Berger, who along with the career grand slam chasing McIlroy were the only players to record an under-par round.

Among the players to miss the cut for the weekend were three-time champion Phil Mickelson, the 2000 and 2004 runner-up Ernie Els and twice winner Tom Watson, who played his final round at Augusta with a six-over 78 to finish eight over for the tournament.

Masters leaderboard: Spieth -4; McIlroy -3; Lee, Piercy -2; Snedeker, Kjeldsen, Matsuyama -1; Aphibarnrat, Willett, Garcia, Lowry, Dechambeau, D. Johnson E.