Will a "Grey's Anatomy" spinoff prove good medicine for ABC?

"Private Practice," the tentative title for the drama featuring Dr. Addison Shepherd of "Grey's Anatomy," was considered an odds-on favorite for the network's fall schedule being unveiled Tuesday.

The spinoff was tested as part of a special episode of ABC's hit medical drama that aired earlier this month. More than 21 million people tuned in, above the season average of 19.1 million for "Grey's."

ABC had no comment Monday on the show's status.

Kate Walsh stars as Shepherd, who leaves behind Seattle Grace Hospital and her ex, Dr. Derek "McDreamy" Shepherd, for a fresh start in Los Angeles. She reconnects with a friend whose medical practice needs an obstetrician, and with the friend's former husband and business partner.

Co-stars in the special included Merrin Dungey, Tim Daly, Taye Diggs, Amy Brenneman and Paul Adelstein.