Looming at the top of this year’s March Madness bracket: Duke and its freshman force of nature, Zion Williamson.

The Blue Devils earned the top overall seed in the NCAA Tournament on Sunday, joining Virginia, North Carolina and Gonzaga as No. 1 seeds for the three-week hoops extravaganza that kicks off this week.

Williamson missed five games after wrenching his knee when his Nike sneaker blew out in a regular-season game last month. He’s healthy again, playing well and not concerned about another potential injury that could impact his status as the likely top pick in the NBA draft later this year.

The tournament starts Tuesday with a pair of play-in games, then gets going in full force Thursday.

The Final Four is set for April 6-8 in Minneapolis, where Duke is the early 9-4 favorite to win it all.

The three teams from the ACC as No. 1 seeds ties a record for one conference.

“They earned their right to be there,” said Stanford athletic director Bernard Muir, the chair of the selection committee.

Virginia gets a top seed for the second straight year, hoping to avoid another colossal embarrassment; the Cavaliers will face Gardner-Webb a year after becoming the first top seed to lose to a No. 16 since the bracket went to 64 teams in 1985.

The bracket, as always, included a few surprises and a few more debatable decisions from the selection committee that’s been holed up at a Manhattan hotel this week, crunching the numbers.

Mid-major Belmont made it off the bubble — one of seven teams from non-power conferences to earn at-large bids. That was the highest number since 2015. Other bubble teams were Temple, Arizona and St. Johns. Missing the tournament were Alabama, TCU and Indiana.

Michigan State made a strong bid for a No. 1 seed with its win Sunday over Michigan in the Big Ten title game. Instead, it was put on the `2’ line, with a potential Elite Eight matchup against Duke in a tough East region.

Muir said Michigan State leapfrogged another No. 2 seed, Kentucky, by winning the Big Ten but “at the same token, we thought Michigan and Michigan State would both be on the `2’ line.”

Conference breakdown

The Big Ten Conference has doubled its presence in the NCAA Tournament a year after its fewest picks in a decade.

A record eight Big Ten schools were selected for the 68-team field on Sunday, the most for any league. The ACC, which had three of the No. 1 seeds, and the SEC each got seven teams. Six Big 12 schools made the field.

There were only four teams from the Big Ten last year, when Michigan did make it to the NCAA championship game before losing to Villanova. That was the fewest since only four teams in 2008, when the league had 11 men’s basketball teams overall instead of the current 14.

Regular-season co-champions Michigan State and Purdue are in, along with Michigan, Iowa, Maryland, Minnesota, Ohio State and Wisconsin. The Spartans beat the Wolverines in the Big Ten Tournament final Sunday.

Indiana, another Big Ten team, was one of the first four teams left out of the NCAA Tournament.

Eleven different conferences sent multiple teams to the NCAA tourney. The last time that happened was 2015.

“This is a high year for us,” Stanford athletic director Bernard Muir, the chairman of the NCAA Division I basketball committee, said during CBS’ Selection Sunday show. “We were fortunate for the opportunities, especially that fell our way, that we could get more teams, deserving teams, into the field.”

There were seven teams from mid-major or smaller conferences that got at-large berths.

That included Belmont (26-5) getting an at-large bid despite losing in the Ohio Valley Conference Tournament championship game to Murray State (27-4), which got the league’s automatic berth. It is the first time since 1987 that the OVC sent two teams to the NCAA Tournament.

Atlantic 10 regular-season champion VCU (25-7) needed an at-large berth after losing in the conference tournament that was won by Saint Louis (23-12).

The Pac-12, American Athletic Conference and Big East all had three NCAA teams.