According to early ratings data, the channel recorded an all-hours share of just 10.2%, down from its year-to-date Saturday average of 17.5% and trailing BBC One's share of 26.9%. The figure is also the second worst ever performance for ITV1, ahead of the miserable 9.1% share recorded on July 9, 2006.
The channel's top programme of the day was Who Dares Sings!, a new karaoke-themed gameshow fronted by Ben Shephard and Denise van Outen. It drew 3.7m (18.8%) in the 8pm hour but was beaten by BBC One's rival gameshow National Lottery: 1 vs 100 - also fronted by Shephard - with an average of 4.6m (24%).
Ratings slumped to just 1.4m (7.7%) for the movie Wimbledon, shown between 9pm and 11pm, while BBC One's Casualty managed a respectable 5.5m (27.7%).
The best performing show of the day on any channel was Doctor Who, which drew an impressive 7.4m (38.2%) between 7.10pm and 8pm. Spinoff programme Doctor Who Confidential followed with 1.1m (6.8%) on BBC Three.
Elsewhere, Channel 4's Big Brother interested 2.3m in the 9pm hour, with an additional 303,000 watching on the broadcaster's timeshift channel. BBC Two's coverage of Amy Winehouse performing at Glastonbury averaged 1.9m over an hour from 9.30pm.
> Click here to read our interview with Ben Shephard