Graves made both at the foul line with 9.3 seconds left to make it 65-61. But Patrick Ingram scored quickly for Idaho, Eric Stuteville missed a pair of free throws with 3.5 seconds left and Nick Hornsby inadvertently fouled Ingram away from the basket, giving Idaho a chance a chance to tie at the foul line with 0.9 seconds left.
Ingram missed the first off the back of the rim and missed the rim completely on his second - a quick shot intended to give his teammates a chance for a putback.
The Hornets (9-9, 2-5 Big Sky) led 61-52 with 2:14 left but allowed the Vandals (12-9, 4-4) within one just 1:04 later. Ingram scored a quick layup and Chad Sherwood added back-to-back 3-pointers to make it 61-60.
Justin Strings added 17 points and Dreon Barlett scored 10 for Sacramento State.
Sherwood had 22 points and Ty Egbert 11 for Idaho.