The opening full day of the NCAA men’s basketball tournament delivered slightly higher ratings this year as March Madness is off to its highest-rated start in 23 years.

According to Nielsen, CBS Sports’ and Turner Sports’ exclusive second-round coverage on Thursday averaged a 6.0 overnight household rating/14 share, up 3% in rating from last year (5.8). Games aired across CBS, TBS, TNT and truTV.

Thursday’s coverage, which made NCAA Tournament history with four overtime games in one day, showed ratings growth in three of the four telecast windows. Primetime, at least on CBS, seemed to suffer declines, according to preliminary national estimates.

The day got off to a hot start, as the first daytime window (noon-4:45 p.m. ET) averaged a 4.6/15 in the overnights — up 12% from last year and the top rating since 1991. This window included Dayton’s upset of Ohio State (pictured).

The second daytime window (2:45-7:15 p.m. ET) averaged a 5.4/14, followed by a 7.7/15 for the first primetime window (6:45-10:30 p.m. ET) and a 6.2/12 for the late primetime window (9:30 p.m.-1:45 a.m. ET).

The overall tournament average rating, including the NCAA First Four, was 5.6/12 — up 8% from a 5.2/12 last year.