AUGUSTA, Ga. — What had looked like a cakewalk has turned into a horserace. That is what happened to the Masters on Friday when the wind blew, the greens hardened and Jordan Spieth came back to the field. Now he will share the final group with someone who knows how to sprint to the finish line.

Spieth still is in first place at 4 under par through two rounds, despite having failed for the first time to break or match par at Augusta National. The defending champion shot 2-over 74 on a tough day. He did continue to make history, tying Arnold Palmer’s record of having led the Masters for six consecutive rounds. But he has a bunch of golfers in close chase, led by Rory McIlroy, who is only one stroke behind.

McIlroy had said before the tournament began that he doesn’t “want to be left behind” in the current heady competition between Spieth and Jason Day, winners of three of the past four majors. He has not generated the same excitement as have the other two, even though McIlroy is the one who has a chance to complete the career Grand Slam, having already won the U.S. and British Opens and PGA Championship.

“Look, I know it’s a very big weekend for me. I know that,” McIlroy said, after having birdied three of the final six holes to shoot 71 and end up at 3 under. “I just have to be completely 100 percent focused on the task at hand.”

Early in the front nine Friday, Spieth birdied two of his first three holes and was four clear of the field. At one point, he was seven shots ahead of McIlroy. But the hole locations were more difficult at Augusta than they had been Thursday and the other conditions grew tougher. The result was something like this: Masters slick greens, British Open winds, U.S. Open scores.

Spieth said he hit a 4-iron into the first hole and watched the ball stick. By the time he reached Amen Corner — the 11th, 12th and 13th holes — his 9-iron shots were bouncing over greens. Plus, every golfer had to be wary of the wind even on putts because the breeze could affect the roll.

So it is not just McIlroy who is in the hunt. It is Danny Lee and Scott Piercy at 2 under, Brandt Snedeker, Soren Kjeldsen and Hideki Mastuyama at 1 under and a bunch close behind them.

“I mean, there is potential for someone to shoot a few under and move up into the lead from outside the top 25,” Spieth said, telling reporters that he will use the vexing back nine Friday as “a learning experience.”

“It was very tough to stay cool. It’s a lot easier said than done,” he said, drawing laughs when he added, “I mean, you guys try it.”

An example: Sergio Garcia was alone in second, at 4 under, on No. 9. He hit a long, straight drive and an approach that was so good that the gallery cheered. But the ball checked up, rolled down the green’s false front and landed at the bottom of a hill. Twice Garcia chipped up, only to have the ball roll back to his feet. He made 6 and finished at par.

Day, who shot 73 but is only five back, said, “You’ve got to hit it on the right gust at the right time, pick the right shot.”

Golf fans might believe the winds conjured a dream final pairing for Saturday. Spieth and McIlroy acknowledged the excitement potential. But McIlroy said, nodding to an Augusta member’s green jacket, “I need to focus on me and focus on everything I need to do well, to hopefully be sitting here Sunday with one of those on.”