Martin Ureta raced to the turn in just 32 to lead the BMW Italian Open during the first round.
A graduate of the University of North Carolina, the Chilean had five birdies in six holes from the fifth.
Ureta then parred the long 11th and had to get up and down from off the green at the par three next.
At five under he led the way from English pair Graeme Storm and Robert Rock, who set the clubhouse target at five under after rounds of 67.
Meanwhile Colin Montgomerie was in danger of being upstaged by a playing partner almost 30 years his junior in the first round in Turin.
Montgomerie will turn 47 next month and won his first European Tour Order of Merit title in 1993, the year Italian prodigy Matteo Manassero was born.
Manassero, 17, is just one of a highly-talented group of youngsters taking the golfing world by storm, with Northern Ireland's McIlroy turning 21 on Tuesday - two days after his stunning win at the Quail Hollow Championship - and Japan's Ryo Ishikawa, 18, carding an amazing final round of 58 to win in Japan on the same day.
Montgomerie admits he was not "anywhere near" as good as Manassero at the same age - the teenager was 13th in The Open Championship last year at 16 and 36th in the Masters Tournament last month.
Manassero picked up another birdie on the seventh and eventually signed for a two under par 70, while Montgomerie could only manage a four over 76.
"He was very impressive, to do that as a 17 year old today," Montgomerie said of Manassero. "He has a good future ahead of him and I wish him all the best."
