The two programmes overlapped for 25 minutes from 7pm, during which Strictly had 9.35m to its rival's 7.45m.
Overall, the quarter final of Strictly pulled in 9.11m (39.5%) from 6.05pm, a fall of 700k week-on-week. The peak audience was 10.18m (43.4%) at 6.55pm.
The X Factor's semi-final averaged 9.72m (39.1%) between 7pm and 8.15pm, a week-on-week fall of more than 2 million viewers. The peak audience was 11.62m (46.1%) at 8pm.
The later X Factor results show, in which former favourite Diana Vickers was voted off, had an impressive 9.77m (39.6%) between 8.45pm and 9.15pm.
The surprise elimination result helped boost the audience for ITV2's The Xtra Factor, which pulled in 1.93m (9.6%) from 9.15pm to 10pm. The pre-results show managed 659k (3.1%).
Harry Hill's TV Burp had a huge ratings increase as a result of being sandwiched between the two halves of The X Factor at 8.15pm. This week's episode put in 7.74m (32%) over 30 minutes.
On BBC One, the National Lottery draw interested 5.62m (23.5%), then Casualty had 5.45m (22.3%). Comedy Outnumbered drew 3.98m (17.1%) from 9.10pm.
The British Comedy Awards pulled in 3.96m (19.2%) for ITV1 over 90 minutes from 9.15pm. The last time the programme was broadcast - on December 13, 2006 - it managed 5.02m (23%). ITV2's backstage programme was seen by 316k (2.1%) from 10.45pm.
On BBC Two, the concluding half of Boris Johnson documentary After Rome: Holy War and Conquest interested 1.68m (6.9%) at 8.10pm, then repeats of Have I Got News For You and Never Mind The Buzzcocks brought in 2.46m (10.7%) and 1.55m (7.6%) respectively.
Five's double helping of NCIS delivered audiences of 838k (3.4%) and 1.15m (4.7%) from 7.15pm, then CSI: New York had 1.82m (8.2%) at 9.10pm. Law & Order: Criminal Intent followed with 1.22m (7.1%).
On Channel 4, movie The First Wives Club kept 0.92m (3.8%) over two hours from 7.10pm, then a rerun of The Devil's Whore appealed to 0.52m (2.3%). Thriller movie Along Came A Spider averaged a decent 1.07m (8.3%) from 10.15pm.
ITV1's average share fell 11 points to 30.3% (last week: 41%) in primetime, while BBC One was up to 23.4% (21.1%). BBC Two was third with 7.1% (6.5%), followed by Five with 5.5% (4.5%) and Channel 4 with 3.7% (2.6%).
Ratings data supplied by Attentional