The NCAA Tournament is undergoing its biggest change in more than 40 years as the field grows from 68 to 76 for the 2026-2027 season, which tips off Sunday night with a game between Notre Dame and Villanova in Rome. It's the most significant expansion to college basketball's postseason since the tournament grew from 48 teams to 64 teams in 1985.

While expansion from 64 to 65 in 2001 and 68 in 2011 created pre-first-round action, this step takes it to a new level. The newly dubbed "Opening Round" will replace what was previously known as the First Four and feature 12 total games.

Dayton, Ohio will still serve as one host site for the preliminary action, like it did for the First Four. It will be joined in that venture by Wichita, Kansas. Both cities will host a total of six games apiece across the Tuesday and Wednesday following Selection Sunday.

By Thursday, the bracket for the first round will look the same as it always does on Thursday of the tournament's first weekend. But the path to get there will look and feel different.

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Under the old format, 60 of the 64 teams that played in the first round started their tournament journeys in the first round. Now, just 52 of 64 teams that will be in action on Thursday/Friday for the first round will be beginning there. The other 12 will be coming off Opening Round victories.

What will it all look like? With the 2026-27 season just days away, here is our preseason Bracketology projection.

2027 Bracketology

Last Four In

First Four Out

Duke is the No. 1 overall seed

While Florida landed at No. 1 in the AP preseason poll, Duke is the No. 1 overall seed in CBS Sports preseason Bracketology. The Blue Devils return four key rotation players from a 35-3 team and supplemented the group with the nation's No. 2 freshman class and No. 11 transfer haul.

Among the newcomers are preseason All-ACC first-teamer John Blackwell from Wisconsin and 17-year-old phenom Joaquim Boumtje Boumtje, who will team with Patrick Ngongba to give Duke an imposing front court. The Blue Devils confirmed their promise in the preseason by crushing Tennessee 103-64 and then edging Kansas 90-84 on the road.

Why Duke over Florida here? The Blue Devils have a much easier path in the ACC than the Gators, who must battle through a stacked SEC that features challenges almost every night.

Squeeze on single-bid leagues and mid-majors

For the past two NCAA Tournaments, 31 automatic bids were awarded to the big Dance for teams who won their conference tournaments. With the Pac-12 returning to the fold as the 32nd Division I conference this season, the number of automatic bids is increasing back to 32.

Of those 32 conferences producing automatic qualifiers, history says at least seven are likely to produce multiple bids. Last year, eight leagues produced multiple bids.

If eight conferences produce multiple bids again in 2027, that would leave 24 one-bid leagues. While it's theoretically possible that an unexpected conference tournament champion from a multi-bid league could be relegated to the opening round, the more likely outcome is that 12 of the 24 NCAA Tournament representatives from single-bid leagues will be stuck playing in the Opening Round.

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Previously, just four teams from single-bid leagues — all clustered as No. 16 seeds — played in the First Four. As a result, 29 of the 31 automatic qualifiers were still around for the first round last season while the other 35 teams playing on Thursday/Friday were at-large squads.

This year, just 26 automatic qualifiers will still be around once Thursday arrives, while 38 at-large teams will still be afloat. What does that mean? Fewer mid-major teams will be a part of the true Thursday/Friday madness. The 76-team format clears the path for a greater share of the first-round spots to be taken up by at-large teams, most of whom will come from high-major conferences.

While this change does technically clear the way for more mid-major teams to win games in the NCAA Tournament, those wins will be coming on Tuesday and Wednesday against other mid-major teams and not during the traditional first weekend action.

Full conference breakdown

Here is the full rundown of multi-bid leagues from the preseason 76-team CBS Sports Bracketology.

SEC (13): Florida, Alabama, Vanderbilt, Tennessee, Texas, Arkansas, Kentucky, Auburn, Texas A&M, Georgia, Missouri, Oklahoma, LSU
Big Ten (10): Illinois, Michigan State, Michigan, Purdue, Nebraska, Wisconsin, Ohio State, UCLA, Iowa, Indiana
Big 12 (9): Houston, Arizona, Texas Tech, Kansas, Iowa State, BYU, Baylor, Cincinnati, West Virginia
ACC (9): Duke, Virginia, Louisville, Miami, North Carolina, Clemson, SMU, NC State, Florida State
Big East (5): UConn, St. John's, Villanova, Marquette, Providence
Pac-12 (3): Gonzaga, Utah State, Colorado State
Atlantic 10 (2): Saint Louis, VCU