New BBC detective series Luther suffered a massive drop in its audience on Tuesday night.
The programme, which stars The Wire's Idris Elba, appealed to 4.05m (17.9%) on BBC One from 9pm, representing an almost 1.3m week-on-week drop.
However, the show still comfortably won the 9pm hour, after The Bill attracted just 2.66m (11.7%) to ITV1.
Holby City, which was not shown last week due to a BBC News special on David Cameron becoming prime minister, pulled in 5.71m (26.7%) for BBC One in the 8pm hour.
On ITV1, documentary series Children's Hospital appealed to 2.5m (12.4%) from 7.30pm, and Who Wants To Be A Millionaire gained 3.19m (14.9%) in the 8pm hour.
BBC Two's Coast averaged 1.61m (8.4%) from 7pm. It was followed by Theo's Adventure Capitalists, with 900k (4.2%), a 360k week-on-week increase.
The Story of Science took 1.72m (7.6%) for BBC Two in the 9pm hour, but it was beaten by Heston's Ultimate Feast, which pulled in 1.86m (8.3%) for Channel 4 and 217k (1.2%) on timeshift.
Also on Channel 4, Supersize vs Superskinny averaged 1.9m (8.9%) in the 8pm hour and 254k (1.1%) on timeshift, and documentary Our Daughter: The Mermaid had 1.52m (9.1%) from 10pm and 118k (1.3%) on timeshift.
Cowboy Builders saw an impressive 330k week-on-week increase to 1.34m (6.5%) on Five in the 8pm hour.
Later on the channel, CSI appealed to 2.02m (8.9%) from 9pm to 10pm.
Overall, BBC One dominated primetime with 24.5% compared to ITV1's 14.7%. Channel 4 took third place with 7.4% (+1: 0.9%), ahead of BBC Two with 6.2% and Five with 5.8%.
Elsewhere, the final episode of Blood, Sweat And Luxuries pulled in 612k (2.7%) for BBC Three in the 9pm hour, then a repeat of EastEnders managed 996k (5.1%) from 10pm.