FIRST OFF . . .

Lyricist-songwriter Carole Bayer Sager will be the first guest host under Fox Broadcasting’s new revolving-host format for its low-rated “The Late Show,” which dumped Joan Rivers last Friday. A spokeswoman for Sager said Monday that the tunesmith’s husband--songwriter Burt Bacharach--would be a guest on the Friday show at 11 p.m., which will be the first new show since Rivers’ departure (reruns will be used until then). Fox Broadcasting spokesman Brad Turell confirmed Sager’s booking and added that Suzanne Somers (Monday), George Carlin (May 27) and Buck Henry (May 29) have also been named as guest hosts. Turell said that negotiations are continuing in an effort to keep Rivers as a regular among the guest hosts for the late-night talk show.