The 1-3-1 – "13" – didn't make an appearance until the Duke victory on Feb. 20. Tokoto has been the primary point man in this zone with the point guard being responsible for running the baseline.
"They're two completely different defenses," Williams told reporters on Friday. "The 1-3-1 is really unusual the way we try to play it. I'll still say ‘try,' because we haven't gotten there yet. The 3-2 is a more traditional zone to try to make sure somebody shoots it from the outside and you have a hand in their face and you get the rebound.
"The 1-3-1, we're trying to hopefully cause some turnovers and take them out of what they practice. Everybody practices a zone offense, but there's very few teams that spend a lot of time every year against something a little unusual like the 1-3-1 the way we spread it out."
According to Williams, his team practiced its zone defense "almost none" in the preseason before adding a weekly 10-minute practice period early in the schedule. Once the coaching staff decided they would need to utilize the zone more in games, those 10-minute periods doubled.
UNC practiced its zone for 10 minutes on Thursday, its first practice since Monday's win over Notre Dame.
There are weak spots in all defenses, and these zone schemes are no different.
"With the 3-2, the big man has to come out and cover the corner until the guard can get there, so there's that exchange point that makes it a little tough to handle sometimes, especially against a team like Duke that can have four or five shooters in the game," sophomore guard Marcus Paige said.
The weak spot of the 1-3-1 can be found on the interior with defenders having to collapse to help Paige or Nate Britt if the ball is forced inside.
Both have unique benefits.
"[The 1-3-1] pushes the offense out and we try to keep them out of scoring position," Paige said. "We want them playing catch two feet inside of halfcourt. Whereas the ‘3' defense is a little bit more packed in and it covers each spot without putting a whole lot of pressure on the offense. It's just kind of a thing we go to if we're in foul trouble or if we want to give them a different look.
"The 1-3-1 is a little more aggressive in terms of trying to steal the ball. They're both useful and we'll probably use both of them at times tomorrow."
While the 3-2 zone is a way to take away interior looks while stressing perimeter options, according to Tokoto, the 1-3-1 is geared more toward turnovers through chaos.
"If there's a lob pass going from near midcourt to the corner, the job of those two guys closest to the ball is to create havoc," Tokoto said. "Trapping is a great way to do it. It creates run-outs because the other guys can fly around and guess where the next pass is going."
Duke did most of its damage early in Chapel Hill by breaking down UNC's defenders off the dribble and getting into the lane. By removing those penetration lanes in switching to zone, the Blue Devils were often forced to settle for either deep or contested 3-point attempts.
Duke scored 13 points over the final 12:11 at the Smith Center and missed 11 of its final 12 3-pointers.
Those issues have plagued the Blue Devils ever since. Duke's last three opponents – Syracuse, Virginia Tech and Wake Forest – have all played some variation of a 3-2 zone.
Duke has shot 25.8 percent (24-93) from 3-point range since UNC threw the 1-3-1 its way midway through the second half.
"We cannot be a team that just relies on perimeter jump shots," Duke associate head coach Steve Wojciechowski said on Thursday.
Williams assumed that Duke has spent time prepping for UNC's 1-3-1 zone ahead of Saturday night. Everyone watching will be anxiously waiting for the next chess move to be played.