Only 16 teams remain in the N.C.A.A. men’s basketball tournament entering Thursday. By the end of this weekend, the field will be whittled down to the Final Four.

Four games will take place Thursday, split between San Francisco and San Antonio, before four more on Friday in Philadelphia and Chicago. Eight teams will remain entering the weekend, with two games Saturday and two on Sunday.

Nine different seed lines and eight conferences remain among the round of 16. Here’s what to watch for entering the Thursday games.

Three No. 1 seeds remain, but their paths aren’t easy.

Baylor was knocked out on Saturday by eighth-seeded North Carolina, making this the fifth straight tournament in which the reigning national champion was ousted before the round of 16. Yet three No. 1 seeds remain: Gonzaga (28-3), the top overall seed, Arizona (33-3) and Kansas (30-6).

Under Coach Mark Few, Gonzaga is the only team that has reached the round of 16 in each of the last seven tournaments, and it has played in two of the last four championship games. But its path to the Final Four in New Orleans is anything but easy. After surviving ninth-seeded Memphis, 82-78, in perhaps the most entertaining game of the tournament, the Bulldogs will face No. 4-seeded Arkansas in San Francisco (Thursday, 7:09 p.m. Eastern time, CBS), and then would get the winner between the No. 2 seed Duke and No. 3-seeded Texas Tech in the West region. Gonzaga enters as a 9½-point favorite over the Razorbacks.

Kansas is an 8-point favorite over No. 4-seeded Providence, the Big East regular-season champion, on Friday in Chicago in the Midwest region.

But Arizona is just a 1½-point favorite over fifth-seeded Houston in San Antonio in the South (Thursday, 9:59 p.m. Eastern, TBS). If you’re looking for an upset, Houston is your best bet. The Cougars are in the top 10 in both offensive and defensive efficiency according to Ken Pomeroy’s rankings, meaning they tend to get a good shot while their opponent does not.

At least one No. 1 seed has reached the Final Four in nine straight tournaments, and multiple No. 1 seeds have reached the round of 8 in seven straight tournaments.

Coach K is still in the hunt for a sixth championship.

Duke (30-6) survived and advanced against seventh-seeded Michigan State on Sunday, extending Coach Mike Krzyzewski’s career for at least another week. Still, the Blue Devils will have their hands full with an older Texas Tech team ranked No. 1 in defensive efficiency by KenPom. The Red Raiders (27-9) are allowing just 13 points in the paint per game in the tournament, the fewest in the field. They will look to play a physical game that disrupts Duke’s offensive flow (Thursday, 9:39 p.m. Eastern, CBS). The Blue Devils feature five potential N.B.A. draft picks, led by the freshman forward Paolo Banchero, who averages 17.0 points and 7.9 rebounds per game.

“I’m not that excited,” Mark Adams, Texas Tech’s first-year coach, said of facing Duke. “I don’t know if anybody is excited about playing Duke.”

Krzyzewski has “always been a mentor of mine, someone I looked up to,” Adams added. “Not only is he a great coach, but a great person. Just done so much for basketball. And he’s built a program which we all admire and respect. It’s just one team to the next, he’s got a dynasty he’s built. So our hat’s off to him.”

Should Duke advance, it could get a rematch against Gonzaga in what would be the highest-profile game of the tournament. The Blue Devils beat the top-ranked Bulldogs, 84-81, on Nov. 26 in Las Vegas with Banchero scoring 21 points and the junior forward Wendell Moore having 20 points, 6 rebounds and 6 assists.

The A.C.C. and Big 12 lead the way, but the Big Ten is struggling again.

The Atlantic Coast Conference was maligned for being down throughout the season, yet here it is with three teams — Duke, North Carolina and Miami — in the round of 16. The Tar Heels knocked off a No. 1 seed, and the Hurricanes routed a No. 2 seed, Auburn, by 18 points.

Miami Coach Jim Larrañaga trolled Charles Barkley, the Naismith Hall of Famer who played at Auburn, immediately following the No. 10-seeded Hurricanes’ 79-61 victory on Sunday. Barkley, working as a TV analyst during the tournament, had said before the game that he would celebrate by taking his shirt off if Auburn won.

“I listened to Charles Barkley tell the CBS crew that if Auburn won, he would take off his shirt,” Larrañaga said. “And I thought to myself, ‘Man, no one wants to see that, Chuck.’”

The Big 12 Conference also has three teams remaining in Kansas, Texas Tech and Iowa State, which took out third-seeded Wisconsin, a Big Ten regular season co-champion, and next gets Miami.

The Big East has two schools remaining in second-seeded Villanova, which won N.C.A.A. championships in 2016 and 2018 under Coach Jay Wright, and Providence.

The Pac-12 also has two schools remaining, Arizona and fourth-seeded U.C.L.A., which plays North Carolina on Friday. A West Coast school hasn’t won the title since Arizona in 1997.

The Big Ten once again is coming up short. It sent nine teams to the tournament, the most of any conference, but only two remain. No. 11-seeded Michigan will face Villanova in San Antonio (Thursday, 7:29 p.m. Eastern, TBS). No. 3 Purdue, the runner-up in the Big Ten tournament, will meet upset-minded St. Peter’s, a No. 15 seed, on Friday in Philadelphia.

A year ago, the Big Ten also put nine teams into the tournament, with only Michigan reaching the round of 8.