The Gonzaga Bulldogs (6-0), who host North Dakota State at the McCarthey Athletic Center in Spokane, Wash., have been ranked third since the preseason poll.
But their 89-87 win over No. 1 Duke in the Maui Invitational title game propelled the Bulldogs to the No. 1 spot.
The Jayhawks were displaced by Duke after the Blue Devils' 118-84 destruction of then-No. 4 Kentucky on opening night.
Regardless of who's No. 1 and No. 2, the Zags are in uncharted waters - even as a program that has been one of the nation's most successful over the past two decades.
Gonzaga has been No. 1 before - in 2013 and 2017 - but never this early in the season. Their No. 3 preseason ranking was the best in program history.
Now, the bluebloods expect the Bulldogs to be there soon.
"So, I talked to Mark before the game and told him how much I liked their team and what he's done," Duke head coach Mike Krzyzewski said following the Maui Invitational title game. "He's done a marvelous job with his program, and it's an honor to play against him and their fan base, and it's a great game for college basketball. ... That was really good basketball."
To beat Duke, the Zags were nearly flawless for the first 30 minutes. After the Blue Devils' hot start to the season, some wondered if they could be beaten.
But the Zags did just that, making shots from all over the court while building a 16-point lead in the second half.
Then came the Duke rally.
While the Blue Devils tied the game in the late going, the Bulldogs held on to win 89-87, thanks to their defense -- Duke's R.J. Barrett was stopped five times in the final 57 seconds. Gonzaga forward Rui Hachimura, the Maui MVP, had an idea why his team conquered the Blue Devils' heralded freshmen.
"We have more experience than those Duke guys," he told the (Spokane) Spokesman-Review.
Hachimura and frontcourt mate Brandon Clarke are juniors. Wings Zach Norvell and Corey Kispert are sophomores, while point guard Josh Perkins and his backup, Geno Crandall, are seniors.
Gonzaga going through Illinois, Arizona and Duke for the Maui title without junior forward Killian Tillie, projected as one of the Zags' two best players before the season, speaks well of the team's chances down the road.
The Bulldogs face a different level of opponent on Monday.
North Dakota State (2-4) is one of the younger teams in the nation; there isn't a senior on the roster. The undersized Bison will be at a distinct disadvantage against the Zags.
But the Bison have depth, as well as some players who can score.
"We have talented pieces," head coach Dave Richman told the Grand Forks Herald after an 82-63 win over UC Santa Barbara earlier this month. "We have a bunch of guys who can shoot it and that spaces the floor. You saw different guys get going at different times and that's a luxury that we have."