Georgia Tech (22-7, 8-5 ACC) won its second straight and improved its home record to 12-2. Ceter DeGraffenreid had 25 points for North Carolina (17-10, 5-8), which has lost seven of eight.
Sasha Goodlett gave Tech the lead for good at 56-55 with 1:36 left when she made one of two free throws. A 3-point basket by DeGraffenreid with 28.2 seconds left got the Tar Heels to 59-57 but Tech made five of six free throws the rest of the way — two each by Metra Walthour and Montgomery and one by Deja Foster, who added 11 points.
Ardossi, Tech's leading scorer, had 12 second-half points and was 10 for 10 at the free throw line.
Tech won despite 23 turnovers. North Carolina had 21.
North Carolina had been ranked as high as No. 4 and had won at least 28 games in previous five seasons, including four straight ACC tournament titles and two Final Fours.
Tech had lost 15 of its last 16 games to the Tar Heels, including 89-78 earlier this season in Chapel Hill. In that game, the Yellow Jackets hit on only four of 20 3s and had 22 turnovers. The Yellow Jackets only win during that period was 66-62 in Atlanta on Jan. 22, 2009.
Tech led 27-24 at the half despite 17 turnovers. Montgomery led the Yellow Jackets with nine points, including their first seven of the game. DeGraffenreid led North Carolina with nine points. The Tar Heels had 12 turnovers and shot only 34.5 percent (10-for-29) from the field and missed all six 3-point attempts.