• by David Goetzl  @dgoetzl, July 26, 2010

"Mad Men's" 40th episode proved to be its most-watched Sunday. The debut of season four drew 2.9 million viewers from 10 p.m. to 11 p.m., marking a 5% bump over the premiere a year ago, and a series high.

It also drew a 2.3 household rating, up 10% versus season three's launch and another record for the AMC show. An average 30-second spot on first-run episodes of "Mad Men" commanded about $20,000-$25,000, according to a recent trade media report.

Most critics who watched the debut of season four gave it high marks.

The network did not yet release ratings in the advertiser-coveted 18-to-49 demo. Nor was there an indication whether it gave a lift to the pilot of new series "Rubicon," which followed it on Sunday.

The Sixties ad show does receive a significant amount of time-shifted viewing, which should give its numbers a bump over the next few days.