Strictly began at the earlier time of 7.25pm and averaged 7.72m (32.9%) until 9.05pm, a fall of around 700k on Friday night's opening episode.
The X Factor put in 9.27m (38%) for ITV1 between 8pm and 9.15pm, a week-on-week fall of 1m and the show's lowest performance of the series to date.
The X Factor peaked with 10.72m (42.6%) at 8.55pm, while Strictly hit a high of 8.68m (35.7%) five minutes later.
The clash also had an effect on ITV2 spinoff show The Xtra Factor, which was down to a low of 905k (4.5%) at 9.15pm.
Earlier, the second series of Merlin launched to a healthy 5.08m (27%) for BBC One at 6.40pm. It beat ITV1's The Cube, which put in 4.67m (22.8%) in the 7pm hour.
After Strictly on BBC One, the latest Lottery draw was seen by 6.27m (27.2%), then a new episode of Casualty brought in 5.33m (24.5%).
ITV1's screening of Casino Royale, starring Daniel Craig, averaged 5.09m (25.8%) between 9.15pm and 11.05pm. The concluding part managed 3.46m (32.1%) between 11.20pm and 12.15am.
On BBC Two, Dan Snow's profile of Aztec leader Montezuma interested 1.14m (4.7%) in the 8pm hour, then a repeated edition of Have I Got A Bit More News For You grew the audience to 1.89m (8.2%). Mock The Week followed with 1.57m (7.3%).
A screening of Lord of the Rings: The Fellowship of the Ring averaged 1.15m (5.1%) for Channel 4 between 7pm and 10.15pm, then a repeat of the first episode of Red Riding delivered 393k (2.8%) over two hours.
An NCIS double-bill put in 678k (3.8%) and 926k (4.2%) for Five from 6.25pm, then at 8.15pm, CSI: NY took 791k (3.2%). CSI had 882k (4%) an hour later, then Law & Order: SVU improved the audience to 985k (5.7%).
ITV1 just pipped BBC One in primetime overall, with an average share of 29.3% to its rival's 28.6%. BBC Two was third with 6.6%, followed by Channel 4 with 4.7% (+1: 0.8%) and Five with 4.1%.
BARB ratings data supplied by Attentional