The classic gameshow, which featured 16 Olympic Team GB stars, achieved an average audience of 5.78m (25.6%) between 6.45pm and 8.15pm
Hosted by Gabby Logan and won by boxer Anthony Joshua and oarswoman Helen Glover, the programme was the most-watched broadcast of the day.
The National Lottery: Secret Fortune followed with 4.3m (19%), before 3.26m (14.6%) and 3.18m (15%) caught a double bill of Mrs Brown's Boys catchups.
BBC Two overtook ITV with its combination of Dad's Army (2.4m/10.7%) and Sound of Music retrospective Climbed Every Mountain (2.46m/10.8%) proving too strong for 30 Years of CITV (1.96m/9%) at 6.30pm (+1: 129,000), I Love You've Been Framed (2.43m/10.7%) at 7.30pm (+1: 186k) and new gameshow Dale's Great Getaway, which could only muster 1.47m (6.5%).
Surprisingly, ITV nearly fell behind Channel 4, which commanded 1.86m (8.5%) between 7.15pm and 11.30pm for last Lord of the Rings film The Return of the King, adding 315k on +1.
World's Strongest Man and Stephen King's Bag of Bones led a strong night for Channel 5, with 1.37m (6%) from 8pm (+1: 105k) and 1.35m (7.4%) respectively.
Overall, BBC One scored another primetime victory with 20.5%, with BBC Two soaring to second place with 9.8%, and ITV settling for third with 8.3% (+1: 0.6%). Channel 4 followed with 8.1% (+1: 1.1%), and Channel 5 finished last with a decent 5.7% (+1: 0.5%).
BARB ratings data supplied by Attentional