Ratings Chart Attack!

A time-period switch for “Big Brother” sparked a rise in its ratings, as CBS played musical chairs with its original summer schedule.

Moving its eviction segment from Wednesday to Thursday, “Brother” pulled a 2.3/8 in the 18- to 49-year-old demo, according to preliminary Nielsen numbers.

“Brother” increased 15% from its previous Wednesday average and trumped last week’s “Greatest American Dog,” which moved to “Brother’s” old slot, by 28%.

“Flashpoint” (1.8/6) increased a tick over last week’s time-period premiere, replacing “Swingtown,” which moved to the ratings graveyard known as Friday night.

CBS finished second with a 2.0 rating/6 share.

Fox ended Thursday night in first with a 2.3 rating/7 share, thanks to a flat “So You Think You Can Dance?” (2.8/9) and a special “Don’t Forget the Lyrics” (1.7/6), which tied last week’s season finale of “Are You Smarter Than a 5th Grader?”

NBC was third with an average “Last Comic Standing” (1.9/6) and “Fear Itself” (1.3/4), ending the night with a 1.7 rating/6 share.

“Hopkins” (1.7/5) ended its run on ABC slightly above par, as ABC took fourth with a 1.3 rating/4 share.

The CW was fifth with a 0.6 rating/2 share.