Scot Lee remained ahead of the chasing pack midway through day three after carding three birdies and two bogies on his way out to keep one shot clear of Tullo and American Peter Uihlein.
But Lee had little joy on his way back to the clubhouse, making par everywhere except on the 11th hole where he found his last birdie.
Tullo, meanwhile, kept his tournament score at 204 by carding four birdies and a bogey on the back nine, while Uihlein earned a share of second place with Lee by scoring three birdies and bogie on his way back in.
Denmark's Morten Orum Madsen and Jarmo Sandelin of Sweden are both a further three shots behind on eight-under for the tournament.
Englishmen Chris Paisley and Richard Bland entered the top 10 by finishing the day on scores of 211, with three birdies on the back nine helping Paisley finish four under today.
The best round of the day belonged to Portugal's Jose-Filipe Lima who carded a six-under-par 66.