McKillop hit six 3-pointers to lead a complete long-range turnaround for the Wildcats (1-2). A day after a 2-for-22 effort in a loss to West Virginia, Davidson made 11 of 28 3s.
The Wildcats hit three straight 3s early in the second half, but could not get a lead larger than two points off any of them. McKillop, who made 6 of 11 3-pointers, changed that when he hit consecutive 3-pointers for a 46-40 lead.
McKillop kept the 3-point happy offense rolling with another that gave them a nine-point lead.
Nebraska, which has dropped both games in the tournament, would get the game within one. Jorge Brian Diaz, the only player from Puerto Rico in the eight-team field, made a layup for a 58-56 lead and Jeter's jumper cut it to 63-62.
Diaz scored 13 points.
The Huskers had funky numbers in each half: Nebraska shot 32 percent in the first 20 minutes and led 30-28; then went 12 of 19 from the field in the second and were outscored by five points.
Nebraska even won the battle from the free-throw line, making more shots (23) than Davidson attempted (20).
The difference was at the 3-point line. Jeter made the only two 3s for the Huskers. Cohen, who scored 15 points in the first half, hit two for Davidson and De'Mon Brooks also made two. Brooks hit a big one late as part of his 11 points after Diaz's layup made it one-point game and gave the Wildcats just enough room to keep the lead the rest of the way.
Nebraska's Drake Beranek made two free throws with 29 seconds left to make it 65-64.
Ubel, who had nine rebounds, was called for the crucial travel and a desperation shot was off the mark.
Each team has one more game in the three-day tournament on Sunday.