DeWanna Bonner scored 27 points and fellow sophomore Whitney Boddie came through with 15 points, seven assists, four steals, four rebounds and no turnovers at the point guard spot.
Bonner was was 9-16 from the field and she led the Tigers with nine rebounds while adding two blocks and one steal.
Auburn moves into the round of eight with a Sunday 2 p.m. CDT game at Kansas State, which defeated Illinois on Thursday night.
The Tigers shot 54.7 percent from the field and hit 4-5 threes, all by junior guard Tamela McCorvey, who was 3-3 in the second half on the way to scoring 17 points. The Tigers were 19-27 at the foul line and made key shots down the stretch to preserve their lead.
"We really did a good job of taking care of the basketball down the stretch," said Fortner, who noted she was pleased that her team had just 13 turnovers for the night.
After trailing much of the opening half, the Tigers took a 37-32 lead into intermission. Auburn led almost the entire second half as it improved its record to 21-12 while Virginia Tech finishes at 19-15.
"Everybody stepped up big-time," said Fortner, who liked the play off the bench of Alexis Ogubie after starting forward Jordan Greenleaf got in early foul trouble and played just 16 minutes. "How big was Alexis Ogubie off that bench," she added of the forward who was 3-3 from the field with three rebounds, two blocks, one assist and one steal. "It is tournament time and everybody has got to do their part."
Fortner said Auburn's scouting report saw a possibility for Bonner to have a big night with her quickness and ball-handling skills. "We felt like we could take advantage of their post players," the coach said. "We felt we had the ability to drive from the high post. I thought it was a factor tonight."
Auburn had six fewer turnovers than the Hokies, which helped the Tigers overcome a 31-26 Virginia Tech edge in rebounds. "I thought Whitney played a real solid game," Fortner said of the point guard. "She handled the ball well and understood what we were trying to get offensively."
Virginia Tech was led by 24 points from forward Britney Anderson, who hit 10-15 field goals. Brittany Cook added 14 points for the home team.