Scott May, Kent Benson, Quinn Buckner, Bob Knight and the Indiana team of 1975-76 can rest easy. Again.

The last two undefeated teams in men’s college basketball lost on Tuesday night. No. 1 Baylor lost at home to No. 19 Texas Tech, 65-62, after leading by 15 in the first half. The loss was a shock: Baylor was an 11-point favorite and as the defending national champion had looked imposing all season, beating Stanford by 38 and then-No. 6 Villanova by 19 and winning a strong tournament in the Bahamas.

Also on Tuesday, the other undefeated team, No. 5 Southern California, lost at its Pac-12 rival Stanford, 75-69. A final eight team last season, U.S.C. had started unranked in the Associated Press Top 25 poll, but crept up as it kept winning. (Its unbeaten record was also helped by having three conference games over the holidays canceled or postponed because of Covid issues.)

The losses by Baylor and U.S.C. mean that long-ago Indiana team will retain its distinction as the last undefeated national champion.

At one time, undefeated men’s N.C.A.A. champions were not too unusual.

San Francisco was the first (1955-56), aided immeasurably by Bill Russell and K.C. Jones, and North Carolina matched that the next year. Then U.C.L.A. almost made perfection seem boring, with undefeated seasons in 1963-64 (Gail Goodrich and Walt Hazzard), 1966-67 (Kareem Abdul-Jabbar) and back-to-back in 1971-72 (Sidney Wicks and Henry Bibby) and 1972-73 (losing Wicks, but adding Jamaal Wilkes and Bill Walton). But after Indiana in ’76, perfection ceased.

Two teams did come close. Larry Bird’s Indiana State team of 1978-79 made it to the final undefeated before losing to Magic Johnson and Michigan State. In 1990-91, the reigning champion U.N.L.V. was No. 1 all year and didn’t lose until the final against Duke. Still, the long drought of undefeated teams has continued.

But in recent years there has been a renaissance of perfect regular seasons. Wichita State managed it in 2013-14 before losing in the second round of the tournament to Kentucky. A loaded Kentucky team in 2014-15 that included the one-and-done freshmen Karl-Anthony Towns and Devin Booker fell to Wisconsin in the Final Four. And last season, Gonzaga made it to the final unblemished before losing to Baylor.

On the women’s side, perfect national champions are still a common occurrence. UConn alone has made perfect championship seasons a habit, accomplishing them in 1995, 2002, ’09, ’10, ’14, and ’16. The 1998 Tennessee and 1986 Texas teams have also done it in the N.C.A.A. era.

This year, Colorado is the last undefeated women’s team, but it is ranked only No. 22 because of a relatively weak schedule. That will change if it manages to beat No. 2 Stanford on Friday.

Despite the last undefeated teams falling on the men’s side, you wouldn’t say there aren’t any good teams to fill an entertaining N.C.A.A. tournament: There are still seven teams with one loss and more than 20 with only two.

But none with zero.