Fox, with good performances from ”The X Factor” and the season premiere of ”Bones,” prevailed among young adults on Thursday, but CBS was close behind and led in other categories behind the best Thursday scores to date for ”The Big Bang Theory” and a strong showing by ”The Mentalist.”

According to preliminary national estimates from Nielsen, ”The X Factor” results show averaged a 3.6 rating/10 share in adults 18-49 and 11.3 million viewers overall in the 8 o’clock hour, rising from a 3.3 in the demo at 8 p.m. to a 4.0 at 8:30. It was followed by the season premiere of ”Bones” (3.3/8 in 18-49, 10.0 million viewers overall), which had its best opener in three years and placed a close second to ABC’s ”Grey’s Anatomy” for the hour’s 18-49 lead. For the night, Fox led in 18-49 for a seventh straight Thursday to start the season.

CBS, which led in adults 25-54 and total viewers, opened very strong with ”The Big Bang Theory” (5.1/15 in 18-49, 15.5 million viewers overall), which matched or set records for a Thursday episode in the 8 o’clock half-hour, rising more than 10% from last week when it faced the World Series and ruling as the night’s No. 1 program. It was followed by ”Rules of Engagement” (3.7/10 in 18-49, 11.9 million viewers overall), also up week to week and second to ”X Factor” in 18-49. Despite the presence of crime drama competition for the first time (Fox’s ”Bones”), ”Person of Interest” held steady at 9 (2.7/7 in 18-49, 11.7 million viewers overall), and ”The Mentalist” led its hour (2.9/8 in 18-49, 13.5 million viewers overall), rising about 15% week to week for its best demo delivery since April.

ABC opened meekly with ”Charlie’s Angels” (1.2/3 in 18-49, 5.4 million viewers overall) before surging at 9 p.m. with ”Grey’s Anatomy” (3.5/9 in 18-49, 9.3 million viewers overall), which was down slightly week to week but won its hour in 18-49 and remained the night’s top drama in the category. And closing out the night, ”Private Practice” (2.6/7 in 18-49, 6.8 million viewers overall) was up week to week to place second.

NBC remained fourth, but ”Community” (1.7/5 in 18-49, 3.9 million viewers overall), ”Parks and Recreation” (2.0/6 in 18-49, 3.9 million viewers overall) and ”The Office” (3.1/8 in 18-49, 6.0 million viewers overall) were all up from last week opposite the World Series. Rookie comedy ”Whitney” (2.1/5 in 18-49, 4.3 million viewers overall) was in line with its performance of last week, while 10 p.m. drama ”Prime Suspect” edged up (1.2/3 in 18-49, 4.5 million viewers overall) but remained well behind its broadcast rivals and was probably in a tight battle with corporate cousin USA’s season premiere of ”Burn Notice.”

CW’s ”The Vampire Diaries” (1.5/4 in 18-49, 3.3 million viewers overall) and ”The Secret Circle” (0.9/2 in 18-49, 2.3 million viewers overall) were flat week to week, with the former matching its season highs and topping the 18-49 scores of two Big Four dramas on the night (ABC’s ”Charlie’s Angels” and NBC’s ”Prime Suspect”).

Preliminary 18-49 averages for the night: Fox, 3.4/9; CBS, 3.3/9; ABC, 2.4/6; NBC, 1.9/5; Univision, 1.3/4; CW, 1.2/3;

In total viewers: CBS, 12.9 million; Fox, 10.6 million; ABC, 7.1 million; NBC, 4.5 million; Univision, 3.1 million; CW, 2.8 million.