Though the corporation insists the new show is not intended as a Neighbours replacement, it was commissioned for the post-lunch slot after Five poached its long-running predecessor.
The programme attracted 1.2m (17.5%) yesterday - down 400,000 on the slot average - but its performance may have been distorted by BBC One showing two episodes back-to-back. Blue is lined up to air for 20 minutes from 2.10pm every weekday, but yesterday it ran for 45 minutes from 2.15pm.
A spokesman for BBC One also noted that, as a soap, it would take some time to establish whether viewers would take to Out of the Blue.
"It is a really encouraging start, the performance was consistent with the slot and it won the slot," he added.
"The qualities of Out of the Blue are different from Neighbours - the main soap for the BBC in the daytime is now Doctors, which is performing amazingly well."
BBC One has ordered 130 half-hour episodes of the Sydney-based soap, which gives it an initial six-month run. It does not have a teatime repeat as Neighbours did, and still does on Five.
BBC One also scored a peaktime success last night with Waking the Dead. The crime drama attracted 6.8m (28.5%) at 9pm - up from 6.3m (26.2%) last week and 1.3m above the slot average for 2007.
On ITV1 at the time, Real Crime: Murder at Harvey Nicks drew just 3.5m (14.6%).