American Idol: The first batch of semifinalists is revealed on a new episode of the singing competition (8 p.m. Fox).
Are You There, Chelsea? "Extra's" Mario Lopez guest stars as himself on a new episode of the sitcom (8:30 p.m. NBC).
Rock Center With Brian Williams: Efforts to save endangered rhinos are examined on a new edition of the newsmagazine
(9 p.m. NBC).
20/20: Robin Roberts profiles assorted 2012 Oscar nominees in this new installment (10 p.m. ABC).
American Weed: The medical marijuana industry is explored in this new documentary series (10 p.m. National Geographic).
Royal Pains: The dramedy about a physician (Mark Feuerstein) serving the well-to-do in the Hamptons ends another season
(10 p.m. USA).
Presidential debate: Republican candidates meet in Arizona in the last debate before next week's Super Tuesday primaries (5 p.m. CNN).
Sex for Sale: American Escort: This new exposé delves into prostitution in the 21st century (9 p.m. National Geographic).
Mr. Smith Goes to Washington: James Stewart filibusters like no one's business in director Frank Capra's 1939 political fable (7 p.m. TCM).
Logan's Run: Michael York and Jenny Agutter are on the lam in this futuristic 1976 sci-fi thriller (11:45 p.m. TCM).
Basketball: The Boston Celtics face the Oklahoma City Thunder (4 p.m. ESPN); the Lakers meet the Dallas Mavericks (6:30 p.m. KCAL, ESPN); and the Clippers host the Denver Nuggets (7:30 p.m. FS Prime).
Hockey: The Kings visit the Colorado Avalanche (6 p.m. NBCSP).
College basketball: UC Santa Barbara plays Long Beach State (8 p.m. ESPN2).