A guest appearance by Britney Spears on Monday gave the CBS sitcom "How I Met Your Mother" its highest rating ever.

A guest appearance by Britney Spears on Monday gave the CBS sitcom "How I Met Your Mother" its highest rating ever.

"Mother" spiked to a series high 4.5 preliminary rating among adults 18-49, even as the rest of the CBS comedy lineup fell from last week's record-setting return to original episodes.

Critics were relatively impressed. "Britney the Trainwreck showed how she can still be Britney the Performer," wrote the Associated Press. "Spears proved she can act every bit as well as she can sing," wrote the New York Daily News. "Brit looked slim, (OK she was behind a desk), trim and gorgeous," wrote the New York Post.

The second week of strong "Mother" ratings (10.6 million, 4.5/12) assures the one-time bubble comedy will be renewed for the fall. "Mother" was the fourth-highest-rated show of the evening, and CBS won the night (averaging 12.5 million, 4.4/11).