AUGUSTA, Ga. — Rory McIlroy played his final 45 holes at Augusta National in 15 under and finished a career-best fourth in the Masters.

But it was the first nine of his second round that cost him a chance at winning a third straight major championship and completing the career Grand Slam.

McIlroy went out in 40 on Friday and by Sunday was too far behind to challenge eventual winner Jordan Spieth.

“I can take a lot of positives from it,” said McIlroy, who shot a 6-under 66 in the final round. “I did a lot of things I wanted to do well. I played the par 5s well. Just left myself too much to do after 27 holes of this golf tournament.”

A year ago, McIlroy played the par 5s at Augusta National in even par. Bubba Watson, meanwhile, was 8 under on them for the week and finished eight strokes lower than McIlroy on his way to winning a second Green Jacket.

This year, McIlroy was a combined 13 under on Augusta National’s longest holes.

Putting was a bigger problem. For the week, McIlroy had 118 putts, including 31 each of the last two days.

Still, the 25-year-old world No. 1 feels like each year he learns a little more about the course. He also said he wasn’t pressing despite the stakes — though he did trail Spieth by a dozen strokes when he teed off in the second round and bogeyed his opening hole.

“It’s just a matter of putting it all together,” McIlroy said. “When I missed it, I didn’t miss it that much but when I missed it I missed it in the right spots and I was just a little more efficient and got it up-and-down. I holed out a bit better (Saturday) and today. So all those little things sort of add up and especially when margin of error is so small here.”