Hell hath no fury like a Simon Cowell scorned.

In his latest tantrum, the famously acerbic talent judge let loose on NBC, which extended its season opener of 'The Voice' to three nights -- with the last night vying for couch-potato eyeballs against Cowell's own premiere of 'The X Factor.'

Simon says he had a "gentlemen's agreement" with 'The Voice' creator Mark Burnett that the two shows wouldn't compete against each other, and now says he's "pissed off" about the scheduling switch.

For his part, Burnett says he was “unaware” that the extra night of 'Voice' programming had been added, but Cowell calls, uh, cowpatties on that.

“Give me a break. Like I don't know when my show is [airing],” he told reporters. “I think [NBC] decided to put 'The Voice' against us [as] a spoiling tactic. It's very simple: They don't want people to see this first episode. I think it's mean-spirited and I hope and I pray that it backfires on them.”

And he didn't stop there. Responding to comments 'Voice' judge Christina Aguilera made in which she questioned the judging skills of Britney Spears, one of the new 'X Factor' panelists, Cowell shot back, “Tell her to watch the show. She might learn something."