Only the legendary Seve Ballesteros was younger than the 17 year old Italian, who shone with a two under par 70 in his first round in the professional ranks.
"It was a good round. I played steady for 18 holes," said Manassero.
"I played fairway, green and holed some putts. I really liked how I played today - it was a solid round."
Manassero - a British Amateur champion who finished 13th in The Open Championship as a 16 year old last year before becoming the youngest player in Masters Tournament history when he was 36th at Augusta National last month - carded three birdies and a bogey to lie three behind early pacesetters Graeme Storm and Robert Rock.
His first tee shot at Royal Park I Rivero split the fairway, as Manassero concealed any sign of nerves in front of an encouraging home crowd.
"I was a little nervous, like always on big tournaments," he added. "But I am fortunately getting used to it."
Manassero does not even finish school until 2012 - something he is determined to do despite the obvious nature of his career path.
And one expert who was impressed with the teenager's round was Ryder Cup Captain Colin Montgomerie, who needed six shots more than his young playing partner.
"He was very impressive, to do that as a 17 year old today," Montgomerie said. "He has a good future ahead of him and I wish him all the best."