America really does seem to have its fill of music competition series, as ABC’s ambitious and heavily hyped “Rising Star” opened quietly in the ratings Sunday night.

ABC has ordered special time zone-adjusted preliminary nationals from Nielsen, which will be issued later this morning, but all early indications are that “Rising Star” fell short of expectations, beaten head-to-head by a special edition of NBC’s “America’s Got Talent” that was specifically scheduled to blunt the ABC newcomer from getting off the ground.

On a night of other premieres on cable, including the return of HBO’s “True Blood” and the debut of TNT’s “The Last Ship,” ABC’s “Rising Star” averaged a 1.5 rating/5 share in adults 18-49 and about 5 million viewers overall on the network’s stations from 9 to 11 p.m. During the same window, “America’s Got Talent” did a timeslot-leading 2.1/6 in the demo and 8 million viewers overall — a larger audience than anything (excluding sports and “The Golden Globes”) the net has aired in the Sunday timeslot since May 2011.

In Nielsen’s metered-market overnights, “Rising Star” did a 5.1 household rating/9 share to a 3.2/5 for “America’s Got Talent,” which regularly airs on Tuesdays.

“Rising Star,” based on a successful Israeli format in which viewers vote for contestants in real time via a smartphone/tablet app, premiered a month after the conclusion of a TV season that saw Fox’s “The X Factor” canceled following its low-rated third season, while the net’s “American Idol” limped to its lowest-rated year ever. Even NBC’s “The Voice,” the current music-competition leader, saw some ratings erosion as it wrapped its sixth cycle in May.

The preliminary 1.5 demo rating for “Rising Star” is a bit below the 1.7 for ABC’s most recent attempt in the music competition genre, “Duets,” in May 2012.

“Rising Star” attracted 129,071 tweets on Sunday night, with ABC noting that this was more than double what “America’s Got Talent” drew when it opened its season last month (59,734) and about 30% more than this summer’s season premiere of Fox’s “So You Think You Can Dance” (98,888). The ABC series was easily the most discussed Sunday series on Twitter, drawing nearly three times as many tweets as the special “AGT” (33,000).

The “Rising Star” app has surpassed 1 million downloads, the show announced Sunday, and it was the No. 1 free app at the Apple store for the day.

Leading into “Rising Star” for ABC was the season premiere of ABC’s tired “Wipeout” (1.0/3 in 18-49, 3.5 million viewers overall).