Jay Leno Angers NBC's Robert Greenblatt With Ratings Jabs (Report)

NBC “The Tonight Show”/Paul Drinkwater

Bill O'Reilly, left, and Jay Leno on "The Tonight Show"

Jay Leno may have found himself in hot water with NBC entertainment chief Robert Greenblatt after using The Tonight Show stage to mock the network’s ratings troubles.

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Greenblatt fired off an email to the comedian after a Feb. 28 episode in which Leno skewered the network's falling to fifth place during sweeps month, the New York Times reports.

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During the episode's opening monologue, Leno joked about NBC’s fifth-place status: "We are behind the Spanish-language network Univision -- or, as we call it here in Los Angeles, Cinco de Ratings." Other jokes included: "It’s so bad, The Biggest Loser isn’t just a TV show anymore; it’s our new motto" and "It’s so bad, NBC called Manti Te’o and asked him to bring in some imaginary viewers."

The exchange between Greenblatt and Leno is said to have occurred before The Hollywood Reporter reported March 1 that NBC was discussing an exit plan for Leno, which would see him cede his 11:35 p.m. timeslot in 2014, possibly to be replaced by Jimmy Fallon. NBC has denied the report, but two high-level industry sources told THR the network was considering making an announcement in May.

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The sources indicated NBC was concerned about ABC moving its younger-skewing Jimmy Kimmel Live!  to 11:35 p.m. in January. Leno remains dominant in most ratings categories, including the 18-49 demo, though Jimmy Kimmel bested Leno in his first week in the 11:35 timeslot.

"Kimmel has done extremely well," a network veteran told THR for the March 1 story. "Jay wins overall, but on any given night, it's neck-and-neck in 18-49. I understand where they might have fear and also feel that they own the solution [in Fallon]."

Leno’s rep told the Times there would be no comment on the report.