From 10pm, the fight averaged a slot-winning 2.26m (13%), peaking with 2.9m (19.7%) at 11pm.
Meanwhile, the broadcaster's screenings of NCIS (8pm) and Law & Order: SVU (9pm) took 929k (4.6%) and 1.1m (5.3%).
The Space Shuttle's Last Flight mustered 1.14m (5.7%) for Channel 4 between 7.30pm and 9pm (+1: 177k), then 917k (4.5%) tuned in for Camelot.
Over on BBC Two, classic Dad's Army amused 1.73m (9.3%) at 7.30pm, The Impressionists: Paintings and Revolution interested 988k (4.9%) in the 8pm hour and coverage of the Proms dazzled 659k (3.3%).
Harry Potter and the Chamber of Secrets appealed to 3.57m (21.5%) between 5.30pm and 8.15pm (+1: 512k) on ITV1, after which 2.81m (13.8%) watched Odd One In (+1: 229k). Penn and Teller: Fool Us attracted 3.28m (16%) from 9pm and The Marriage Ref held on to 1.4m (7.8%).
Elsewhere, BBC One's Tonight's The Night with John Barrowman entertained 3.7m (19.8%) at 7pm, while The National Lottery: In It To Win It was the most-watched broadcast of the day with a strong 5.51m (27.4%).
From 8.50pm, Casualty gripped 5.07m (24.2%) for an episode titled 'System Error', before Lee Mack's All Star Cast had 3.05m (15.6%).
Overall, BBC One led primetime with 21.7%, beating ITV1's 15.8% (+1: 2.2%). Channel 5 came in third with 6.4%, followed by BBC Two with 5.3% and Channel 4 with 4.7% (+1: 0.7%).
BARB ratings data supplied by Attentional