Despite a star host (Ryan Seacrest), A-list guests (David Beckham and Common), and a live TV hook, Fox’s new unscripted series Knock Knock Live failed to deliver in its premiere, opening with a paltry 0.5 rating in adults 18-49 and 1.7 million total viewer in the fast nationals. That ties last summer’s improv comedy show Riot (0.5, 1.3 million) as the lowest-rated Fox series premiere ever and one of the lowest on the Big 4. Knock Knock was the lowest-rated program on ABC, NBC, CBS and Fox last night — original or repeat.

Knock Knock didn’t get much lead-in help, with a So You Think You Can Dance 10th anniversary special drawing a 0.7 in 18-49 at 8 PM.

NBC again dominated the night with America’s Got Talent. The two-hour Judges Cuts episode drew a 2.3 in 18-49, down -8% from last week, but could rise in the finals. Hollywood Game Night (1.3) was down -7%.

Elsewhere, CBS’ Zoo (1.0) was even with last week (the summer drama has been growing +50% in Live+7). ABC’s Extreme Weight Loss (0.6) continues its ratings swings, down -25% from last week to a series low in Live+Same Day.