Big Brother eviction night attracted 3.9m viewers, a 23% share. Around 2.1m stayed with the channel for Banzia which attracted a 17% share.
The interactive gambling show, which first ran on Channel 4's sister entertainment channel E4 earlier on this year, features a series of situations on which viewers have to guess the outcome.
Predicaments range from asking viewers to guess which woman out of a line of a topless five has had breast enhancement sugary to predicting the correct outcome of the number of slang words a random 'posh lady' can recount for the word vagina.
In fact the first outing of Banzai attracted the same ratings as the BBC's flagship documentary programme, Panaroma, which last night recorded its lowest ratings since moving to a Sunday slot, when viewing figures slid to just 2.1m.
The programme, an investigation into the Bristol heart babies tragedy, notched up just 12% of the total viewing for BBC1. The slump is expected to put renewed pressure on the BBC to admit its Sunday night gamble has been a ratings flop and move Panorama back to a midweek slot.
When the show was moved in November, the BBC director of television, Mark Thompson, said he would give it six months to 'settle down,' but it has failed to stabilise. During the last month alone it has struggled to pull-in more than 17% audience share.
Otherwise, BBC1 had an encouraging Sunday night, pulling in 31% of the audience and 6m viewers for celebrity vet Steve Leonard's Ultimate Killers at 8:30pm, and a 29% share and 6.1m viewers for the one-off crime drama, Gentleman Thief, at 9pm.
ITV's Where the Heart Is continued to perform well and last night was watched by 7.5m viewers at 8pm, 40% of the audience. John Thaw's the Glass remained consistent with 28%, 5.8m viewers at 9pm.
Channel 4's film premiere of Sleepers pulled in 2.7m, 23% of viewers, at 10pm and Channel 5's 9pm film, Bone Daddy, was watched by 1.9m viewers, a 10% share.
On Saturday BBC1's 'network premiere' of the Devil's Advocate, aired at 9pm, gathered a respectable 32% share, 5.7m viewers while Channel 4's preview of Robbie William's new video, Rob by Nature, at 11:35pm, also proved popular, pulling in 1.5m viewers, a 16% share.
BBC1 new six-part period drama, the Cazalets, got off to a steady start at 9pm on Friday, racking up 5.4m viewers and a 26% share.