American John Daly had a 69 despite two closing bogeys on the Royal Park I Roveri course.
Maybin went 2-under on the front nine and 5-under on the back nine, including an eagle 2 at the 13th with a 116-yard wedge into the cup.
Earlier, Richie Ramsay of Scotland set a short-lived course record with a 4-under 67. The previous record had been a 68 by Seve Benson last year.
Ramsay was tied for second with Christian Cevaer, Marcus Higley and Raphael Jacquelin.
I love the way Im hitting the ball, Daly said. I had a lot of opportunities out there.
The two-time major winner is serving a six-month suspension from the PGA Tour.