Craig Kanada and Andy Matthews share second place after carding rounds of 5-under-par 67. Steve Schneiter, Steve Marino, Jeff McCammon and Rob McMillan are one stroke further back at minus-4.
Tiziani posted six birdies on the day, to go along with an eagle. However, he also dropped one shot at The Atlas Golf & Country Club to cut his lead to just two strokes.
'I put the ball very close to the hole most of the time,' said Tiziani, who won the 2003 Northern Ontario Open. 'I played well today. This ties my best round this season. It is early in the tournament, but if I can have another round like this tomorrow, it will be great.'
Alex Quiroz, Jerome Valentin, Matt Weibring, Kent Fukushima, Jason Higton, Chris Locker and Mauricio Molina share eighth place at 3-under-par 69.
Conrad Ray and Steve Scott head a large group of players one stroke further at minus-2.
Erik Compton, who won this event last year and won two weeks ago at the E-Loan Central Valley Classic in California, will not defend his crown. He was disqualified for not signing his scorecard after his round.