The loss snapped a 15-game winning streak by the Flyers (27-2), who hadn't lost since Dec. 30 against Bowling Green. Dayton had beaten 22 straight conference foes, including last season's tournament title run, going back to a Feb. 11, 2012, loss to St. Bonaventure.
St. Joseph's never trailed against Dayton and led, 35-24, after van Grinsven scored 13 first-half points. Dayton got to within 52-51 with 2 minutes, 45 seconds remaining, but van Grinsven hit a jumper half a minute later, and Erin Shields (Archbishop Carroll) tacked on six free throws in the final 1:11.
Shields finished with 12 points, while Ilze Gotfrida added 10. Ashley Prim grabbed 13 rebounds.
Fordham 66, Temple 55 - Natasha Thames had 15 points and 11 rebounds, Rateska Brown also had 15 points, and Victoria Macauley added 14, but the Owls (14-18, 5-9) fell to the Rams (24-7, 12-2) in the later semifinal at Hagan Arena.
Fordham has won eight straight, including a 70-65 overtime home win over St. Joseph's on Feb. 24.