While many 'Glee' fans have been glued to the action in Season 3, overall viewers for the show are down by a sizable 23%, according to the Los Angeles Times, which quotes the latest figures from Nielsen.

Fox responds by pointing out that ratings are down everywhere. "Across the board, network television has with many returning shows had sort of a slow fall," says Dana Walden, chairwoman of the 20th Century Fox Television studio. "There's a very broad, healthy audience for this show."

While critics debate the reasons why ratings might be down, including overexposure of the 'Glee' brand and controversial storylines, sources say the show will almost certainly be brought back for a fourth season, even if its numbers don't drastically improve.

Even the music of 'Glee' has struggled in comparison with Season 2. While the 'Glee' Cast now officially has the most hits on the Billboard Hot 100 in history, far surpassing former record-holder Elvis Presley, none of the Season 3 tracks had even cracked the Top 40 until the Adele cover medley 'Rumour Has It / Someone Like You,' which became one of the show's biggest hits ever with 160,000 downloads.

Billboard associate director of charts Keith Caulfield tells the Times, "Just when people were kind of suggesting that the show had kind of peaked on the charts, out comes this moment, this single that really catches fire." He adds, "As with any phenomenon, it's going to sort of cool off. 'Glee' has probably just come down to normal popularity, as opposed to stratospheric popularity."

The show is now on break, but returns Jan. 17 with the 'Yes/No' episode.