The Holywood golfer had just seen a putt lip the hole on the last to drop a shot and take his overall tally to -16 for the week, five behind victor Dustin Johnson.
Young fan Eduardo had matched Rory's white Nike hat, pink t-shirt and grey slacks and was in tears when he came face to face with his hero. "I never thought that I would be able to win on the PGA Tour".
"So if I can swing it like I am right now, and keep the putter rolling like I did this week, it's going to be a good year". Just four players in the field were below him.
After a 317 yard drive on the 316-yard par-4 first, Spieth chipped his second shot to 2 feet, which he rolled for one-putt birdie on the hole.
Now a lifetime member of the PGA Tour following his latest triumph, Johnson moved to second in the rankings and he will return to number one in the world the following week based on the two-year computations as neither he nor Justin Rose will play at the Honda Classic. He drilled an iron shot to 5 feet at the 15th and didn't even hit the hole, missed a 6-footer for another birdie at the 17th and ended by two-putting from 13 feet at the last hole.
Johnson won the Mexico Championship for the second time in three years.
Englishmen Paul Casey and Ian Poulter shared third on 273, shooting 65 and 68 respectively in the fourth round, with Thailand's Kiradech Aphibarnrat, who fired 68 to join the pack 10 off Johnson's pace.
Tiger Woods carded a final-round 69 with three birdies to finish on eight under in joint 10th place.
McIlroy asked for similar relief on the next hole and was denied when it was deemed he could not attempt the shot.
McIlroy did all he could, making six birdies in a seven-hole stretch on the back nine, and closed with a 67.
PGA TOUR: In Rio Grande, Puerto Rico, Martin Trainer closed with a 5-under 67 to win the Puerto Rico Open for his first PGA Tour title, a three-stroke victory over four players. To do it before I turn 35 is pretty incredible. The 27-year-old former University of Southern California won twice last year on the Web.com Tour and finished fourth on the money list to earn a spot on the big tour.
Lee, from Australia, finished with a 66 in the round delayed by lightning and rain.
"I misjudged the lie a little bit", he said of his second shot. She also won the 2013 LPGA KEB HanaBank Championship in South Korea.
Spain's Carlota Ciganda was third at 20 under after a 63. "If I know I'm hitting it well and driving it good, it's going to give me a lot of confidence".