Men’s March Madness Sets Opening-Day Viewership Record

March Madness has barely begun, and it’s already setting records. 

Thursday was the most-watched opening day of the NCAA men’s college basketball tournament ever, according to preliminary Nielsen data. TV coverage across CBS, TNT, TBS, and truTV averaged 9.1 million viewers, up 6% from last year.

Viewership shot up further during primetime, averaging 12.2 million viewers to set a first-round record. For context, that’s more than the first semifinal game each of the last four years.

The record Round of 64 numbers come on the heels of a historic First Four on Tuesday night: TruTV drew 2.2 million viewers for North Carolina’s blowout of San Diego State, while Alabama State–Saint Francis took in another 1.4 million. The combined 3.6 million viewers was a record for a Tuesday First Four, up 21% from last year.

During the Round of 64, CBS Sports and TNT Sports typically share viewing figures based on viewing windows, or time slots, rather than individual games. But the broadcasters pointed out in a social media post that primetime coverage was “led by” No. 10 seed Arkansas’s 79–72 upset of No. 7 Kansas. While the Razorbacks and Jayhawks both ended the season outside the AP Top 25 rankings, the game represented a marquee matchup because of head coaches John Calipari and Bill Self. The pair have three NCAA championships and 10 Final Four appearances between them.

When the dust settles, Friday may set even more records. Duke, which is favored to win the entire tournament, took the floor Friday against No. 16 seed Mount Saint Mary’s. The Blue Devils are led by projected No. 1 NBA draft pick Cooper Flagg, who scored 14 points and grabbed 7 rebounds in the 93–49 win after missing two games of the ACC tournament with an ankle injury. With Flagg, the Blue Devils have been must-see-TV, featuring in four of the 10 most-watched regular-season games this season.

While Thursday’s figures are expected to go up when final numbers are released, they do come with an asterisk. Nielsen changed how it tracks out-of-home (OOH) audiences (people who watch games in bars or restaurants, for example) earlier this year. According to the analytics firm, it now tracks OOH audiences in 100% of the contiguous United States. In prior years, OOH audiences in at least one-third of the country—particularly rural areas—were not tracked.