Ratings Chart Attack!

ABC’s “Grey’s Anatomy” reached its best ratings since its season premiere.

The medical drama posted a 6.1 rating/15 share in the 18- to 49-year-old demographic on Thursday, according to preliminary Nielsen Media Research data.

The show increased 7% from last week. “Ugly Betty” (2.5/7) and “Life on Mars” (2.5/7) were on par with last week’s numbers. ABC took second with a 3.7/10.

Leading the night, CBS drew a 3.9/10 and 13.9 million viewers. “Survivor” stayed flat from last week with a 4.0/11 and 12.6 million viewers. “CSI” dipped two-tenths of a percentage point from last week with a 4.9/12, and also pulled in 18.4 million viewers.

“Eleventh Hour” also slid, dropping 10% in adults 18-49 to a 2.8/8 and losing 8% of its viewership with 10.7 million viewers.

NBC stayed even with last week with its nightly 3.3/9 average, with “The Office” leading Thursday with a 4.3/10.

Fox, pulling in a 1.9/5, took fourth with a new episode of “Kitchen Nightmares” (2.0/5) and a “Nightmares” repeat at 9 p.m.

The CW’s “Smallville” (1.9/5) and “Supernatural” (1.6/4) saw big gains week-to-week, moving the needle upwards 36% and 33%, respectively. But preemptions occurred in Pittsburgh due to a Steelers/Bengals game, which more than likely will affect the final data and bring those numbers down.