The Northern Irishman, the current world number three, went ahead on the 15th hole before Na responded immediately.

The two players then halved the next two to send the match to a play-off and McIlroy took full advantage of a bogey from the American on the second extra hole to seal his spot in the next round.

McIlroy will take on another American in Zach Johnson for a place in the last eight.

The four-time major winner will be joined in the knockout phase by world number two Jason Day of Australia, who had been struggling with back spasms on day two, after his opponent, Paul Casey of England, withdrew due to stomach pains.

Day, who lifted the Arnold Palmer Invitational trophy on March 17, will go up against Brandt Snedeker of the United States in the last 16.

World number one Jordan Spieth is also through as he was another player to pick up a third consecutive win, birdieing four of the first five holes on his way to a 3&2 success over compatriot Justin Thomas.

The 22-year-old, who will be keen to lay down a marker ahead of the defence of his Masters title in Augusta next month, will have to negotiate a tricky test if he is to reach the quarter-finals as he will play 2010 The Open winner Louis Oosthuizen of South Africa.

“Even after playing so great the first two days, it still felt like it was a win or go home, you don't want to rely on a play-off,” Spieth said.

“It was a great start, birdieing one and two and that's very important to see a couple of putts go in early.”

American Bubba Watson was the biggest name to exit the contest at the group stage as the world number four suffered defeat to countryman JB Holmes, while England’s Justin Rose, currently ranked seventh in the world, is also out following a 3&2 loss at the hands of Matt Kuchar of the United States.