Though they gave CBS a primetime victory and sent ABC’s “Grey’s Anatomy” and NBC’s “The Office” to their lowest 18-49 audiences of the season, the Sweet 16 games of March Madness didn’t exactly dominate for the Eye, according to fast nationals from Nielsen.

Initial estimates gave CBS’ NCAA men’s basketball tournament coverage a 3.8 rating and 11 share in the 18-49 demo and 11.1 million viewers overall – a slight uptick over the previous week. Despite its overall decline, “Grey’s Anatomy” (3.6/10, 11.4 million) topped basketball after 9:30 p.m., which was approximately when the double-overtime thriller between Xavier and Kansas State ended on the West Coast.

Airing from 9-9:30 p.m., NBC’s “The Office” (3.5/10, 7.2 million) was as competitive as “Grey’s” in the demo.

A boost from “Grey’s” gave a firstrun “Private Practice” (2.9/8, 8.8

million) a timeslot victory (among non-sports programming) at 10 p.m., ahead of NBC’s “The Marriage Ref” (2.5/7, 6.5 million).

At 8 p.m., NBC’s “Community” (2.0/7, 5.1 million) was the winner among scripted shows. Combined with “Parks and Recreation” at 8:30 p.m., NBC finished just ahead of ABC’s “FlashForward” (1.8/6, 6.2 million) in 18-49.

A new episode of “The Vampire Diaries” (1.5/5, 3.2 million) on the CW tied a rerun of Fox’s “Bones” (1.5/5, 6.1 million) in the demo, and at

9 p.m., the CW’s original “Supernatural” (1.2/3, 2.9 million) edged a Fox repeat of “Fringe” (1.1/3, 4.1 million).

Preliminary 18-49 averages for the night: CBS 3.8/11, ABC 2.8/8, NBC 2.6/7, CW 1.4/4, Fox 1.3/4, Univision 1.3/4.

In total viewers: CBS 11.1 million, ABC 8.8 million, NBC 6.0 million, Fox 5.1 million, Univision 3.2 million, CW 3.1 million.