The carrot top saw his Tonight Show post steady ratings decline for the first week after he took over hosting duties.
But on Wednesday night he reversed that trend and showed some growth for the first time.
Many veteran observers including yours truly wondered if Leno's more mature audience would stick with Conan's collegiate humor.
But NBC sources are now saying Conan has bottomed out and may now be positioned for solid audience growth.
Certainly we won't know the outcome until September when Leno debuts his new prime time talk-variety outing weeknights on NBC at 19 p.m. How many viewers will watch Leno at 10 only to decide they've had it with talk and bypass Conan at 11:35?
On Wednesday night Letterman was hardly in top form proffering a seven minute apology to Alaska's governor Sarah Palin who bristled at remarks made about her teenaged daughter. Letterman's guests that night included Kathy Griffin and Stupid Human Tricks.
Conan retorted with Dane Cook, hardly a top of the line guest.
But in the all important adults 18-49 Conan recorded a huge jump and that boost spilled over into Jimmy Fallon at 12:35.
NBC's press releaser said "This is beyond our wildest expectations."
But the battle is only starting to warm up. In September comes the fierce ratings battle. This is summertime, remember, and ratings don't really count.