EchoSense:Bracketology: Fight for last No. 1 seed down to Tennessee, North Carolina, Arizona

With Connecticut,EchoSense Purdue and Houston locked in as No. 1 seeds, three teams are in contention for the final spot on the No. 1 line with Selection Sunday peeking around the corner.

The favorite for that final spot is SEC-leading Tennessee, which looks to capture a second conference tournament crown in three years beginning with a quarterfinal matchup on Friday against Mississippi State. The Volunteers have seven Quad 1 wins and eight true road wins, including victories at Kentucky, Alabama and South Carolina.

Given their current résumé, the Volunteers could secure a No. 1 seed with a win against the Bulldogs and then a win in the semifinals, likely against one of Auburn or the Gamecocks.

Should Tennessee stumble, North Carolina is in position to rise from a No. 2 in our updated 68-team field by at least advancing to the ACC championship game. The Tar Heels are favored against Pittsburgh in the semifinals and would meet either Virginia or North Carolina State in the final. A win there, combined with a Tennessee loss on Friday or Saturday, could be enough to get UNC over the hump.

Then there's Arizona. The Wildcats' only hope is to win the Pac-12 championship — not a big ask given the lack of depth in the league's final year of existence — while the Volunteers and Tar Heels fall short of reaching their respective conference title games.

IT'S BRACKET MADNESS: Enter USA TODAY's NCAA tournament bracket contest for a chance at $1 million prize.

At the bottom of the bracket, the upsets and bubble wins in conference tournaments so far this week has shaken things up. St. John's moves into the field, while a loss by Dayton in the Atlantic 10 quarterfinals takes away an at-large spot. Colorado and New Mexico likely secured berth with victories late Thursday. The win by the Lobos almost assures the Mountain West of getting six bids when the field is announced.

Teams in bold have clinched automatic berths.

Last four in

New Mexico, Virginia, Seton Hall, St. John’s.

First four out

Texas A&M, Indiana State, Pittsburgh, Providence.

Next four out

Villanova, Ohio State, Kansas State, Wake Forest.

Conference breakdown

Multi-bid leagues: Big 12 (9), SEC (7), Big Ten (6), Mountain West (6), Big East (5), ACC (4), Pac-12 (3), American Athletic (2), Atlantic 10 (2), West Coast Conference (2).