The Bachelor (2.3/5) was back for its 17th season last night with a two-hour premiere on ABC. Starring former Bachelorette suitor Sean Lowe, the search for love reality series dipped 4% from its season 16 debut on January 2, 2012. While the fall is small, and 6.81 million viewers watched the premiere last night, it does result in The Bachelor’s lowest-rated season debut to date. Also debuting on Monday was NBC’s Deception (2.0/5). Though the new soap drama’s one-hour pilot pulled in 680,000 fewer total viewers than the network’s Chicago Fire garnered when it debuted on October 10, 2012, Deception did manage to slightly exceed the 1.9/5 rating that the fire fighting series delivered. The show also won its time slot among the 18-49 demo last night. Following up on its Sunday season debut, The Biggest Loser (2.4/6) kicked off NBC’s primetime with another two-hour original show debuting in its regular time slot. The weight-loss reality show was down 17% from Sunday’s airing but still was the ratings topper for the night. The first new Castle (1.9/5) in five weeks followed The Bachelor debut on ABC last night. The most watched show of the night with 8.58 million viewers, the crime-based comedy-drama’s rating was up 12% from its December 3, 2012 show, which was a series low. With 7.402 million watching, ABC won the night for total viewers while NBC took the Adult 18-49 demographic.

After a Bones (0.9/2) encore,  The Mob Doctor (0.9/2) wrapped up its first season on Fox. Watched by 3.30 million viewers, Monday’s episode of the freshman series was up 125% from last week’s original show. CBS went with all repeats on Tuesday with How I Met Your Mother (1.6/4), back-to-back 2 Broke Girls at 8:30 PM (1.5/4) and 9 PM  (1.8/4), Mike & Molly (1.6/4) and Hawaii Five-0 (1.1/3).  The CW had Hart of Dixie (04.1) and Beauty and The Beast (0.3/1) encores.

Deadline's Dominic Patten - tip him here.