ITV1's flagship summer entertainment show - widely praised in the press - could only grab 2.96m (15.3%) in the 9pm hour, adding 263k on +1 - a slight drop week-on-week, and a far cry from the 4.2m who watched the pilot in January.
Hosted by Jonathan Ross, the magic show was beaten by stand-up format John Bishop's Britain, which returned for its second series with 3.8m (19.8%) for BBC One at 9.10pm, virtually the same as last year's launch.
Meanwhile, Casualty reclaimed its crown as the most-watched show of the day, logging 4.79m (24.7%) at 8.20pm for an instalment titled 'When You're Smiling'.
The National Lottery: In It To Win It also performed respectably, picking up 4.44m (24.9%) from 7.30pm, while ITV1's Odd One In concluded with 2.89m (15.2%) at 8.15pm (+1: 155k).
Continuing the Harry Potter season, ITV's repeat screening of The Prisoner of Azkaban appealed to 3.64m (24.1%) from 5.45pm (+1: 519k), while Total Wipeout and Tonight's The Night entertained 1.65m (13.4%) and 3.04m (19.6%).
Dermot O'Leary's The Marriage Ref climbed to a still-poor 1.8m (11%) for ITV1 in the 10pm hour, while BBC One's screening of King Arthur nabbed a slot-winning 2.1m (15.2%).
After cricket highlights scored 1.08m (6.4%) at 7pm, NCIS (8pm), CSI: Miami (9pm) and Law & Order: SVU (10pm) pulled in respective audiences of 828k (4.4%), 1.09m (5.6%) and 1.15m (7%).
Channel 4's showing of Crocodile Dundee II brought in 1.09m (6.1%) from 7pm (+1: 243k), then 943k (4.9%) tuned in for Camelot at 9pm and 713k (4.9%) watched the film Cloverfield from 10pm.
Over on BBC Two, classic Dad's Army amused just 1.39m (7.9%) at 7.30pm. The show turned out to be the broadcaster's best-rated of the entire evening, after The Impressionist: Painting and Revolution interested 1m (5.3%) and Proms coverage dazzled 587k (3.4%).
Overall, BBC One owned primetime with 20.7%, ahead of ITV1's 16.6% (+1: 2.3%). Channel 5 claimed third place with 5.7%, followed by Channel 4 with 5.5% (+1: 0.9%) and BBC Two with 5.1%.
BARB ratings data supplied by Attentional