Elizabeth Williams had 16 points and five blocks to help fourth-ranked Duke beat St. John's, 60-42, as part of the Maggie Dixon Classic.
Haley Peters added 11 points for the Blue Devils (8-0), who defeated the Red Storm in the regional semifinals of the NCAA Tournament last season.
Nadirah McKenith had 19 points to lead St. John's (4-3), which has lost two in a row.
Trailing by one, 11-10, Duke went on a 15-2 run to take control. Alexis Jones' layup capped the spurt, making it 25-13 with 8:18 remaining.
The Blue Devils took a 36-21 margin into the locker room and held St. John's to 29 percent shooting in the second half.