First, Mattice connected on a 3-pointer with 6:48 left, giving CNS the lead for good, and she hit another jumper less than a minute later, accounting for five of her 10 points.
Meanwhile, Stewart, quiet on the offensive side much of the night, hit a layup, jumper and hook shot, all in the last period, then made two clinching free throws with 22.0 seconds left to make it 53-47.
Stewart led the Northstars with 15 points, nearly pulling off a triple-double as she added 10 blocks and nine rebounds. Her mere presence altered Corcoran's approach, forcing them to take outside shots that just didn't fall -- the Cougars didn't make a 3-pointer all night. Irene Hudson, with 14 points, was the lone Corcoran player to score in double figures.
The win improved CNS to 3-0 on the season, as it gets a huge test on Saturday when it faces three-time defending state Class AA champion Rush-Henrietta at Pittsford-Sutherland High School near Rochester.