Robin Williams and Sarah Michelle Gellar Robin Williams and Sarah Michelle Gellar

Round 1 of the battle of returning comedy heavyweights goes to Robin Williams.

The funnyman's sitcom The Crazy Ones opened to 15.6 million viewers and a 4.0 in the adults 18-to-49 demographic Thursday, easily trumping The Michael J. Fox Show, which averaged 7.3 million and a 2.1 for two episodes.

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The Crazy Ones improved on Person of Interest's performance in the slot last year and retained about 70 percent of lead-in The Big Bang Theory, the night's top performer, which pulled in a huge 18.3 million and a 5.3 for its season premiere and grew to 19.5 million and a 5.8 for its second episode. Both Big Bang episodes were up from last year's premiere. Two and a Half Men followed The Crazy Ones with 12.6 million and a 2.9, down six tenths from last season's opener. Elementary (10.1 million, 2.1) closed out the night for CBS down a full point vs. last year.

NBC's The Michael J. Fox Show nearly doubled lead-in Parks and Recreation(3.3 million, 1.3), which was down from a year ago, and matched The Office's premiere rating last year in the slot. Parenthood drew 5.2 million and a 1.6, improving on Rock Center's numbers last year, but down a bit from its previous season premiere.

Both Grey's Anatomy (9.3 million, 3.4) and Glee (5.2 million, 2.0) returned 30 percent down. The X Factor (6.4 million, 2.0) stayed steady with last Thursday's numbers.

8 p.m.
The Big Bang Theory 18.3 million (5.3); The Big Bang Theory 19.5 million (5.8)
ABC: Marvel's Agents of S.H.I.E.L.D. 5.2 million (1.4) (R)
Fox: The X Factor 6.4 million (2.0)
NBC: Parks and Recreation 3.3 million (1.3)

9 p.m.
 The Crazy Ones 15.6 million (4.0)Two and a Half Men 11.5 million (2.9)
ABC: Grey's Anatomy 9.3 million (3.4) [9-11 p.m.]
Fox: Glee 5.2 million (2.0)
NBC: The Michael J. Fox Show 7.2 million (2.1); The Michael J. Fox Show 7.3 million 2.1 

10 p.m.
Elementary 10.1 million (2.1)
NBC: Parenthood 5.2 million (1.6)