It's the Paula Abdul factor. Watching Aguilera is like watching Abdul when she used to be a judge on "American Idol." You know there's going to be a train wreck eventually.
Elsewhere on TV ...
NFL: Cincinnati Bengals at Baltimore Ravens (5 p.m., ESPN); San Diego Chargers at Baltimore Ravens (8:15 p.m., ESPN)
Bachelor Pad (7 p.m., ABC/Ch. 4): A winner is declared in the season finale.
Hell's Kitchen (7 p.m., Fox/Ch. 13): A winner is declared in the season finale.
The L.A. Complex (7 p.m., CW/Ch. 30): Nick gets fired.
MasterChef (8 p.m., Fox/Ch. 13): A winner is declared in the season finale.
Warehouse 13 (7 and 9 p.m., Syfy): A pill is making people taller.
Major Crimes (7 and 9 p.m., TNT): A kidnapping case puts extra pressure on the squad.
Perception (8 and 10 p.m., TNT): Pierce is tipped off about a conspiracy to cover up the murder of a U.S. Senator.
Switched at Birth (9 p.m., ABC Family): Regina's impulsive wedding upsets both families.
Great Performances at the Met (10 p.m., PBS/Ch. 7): Behind the scenes of Robert Lepage's staging of the four-part ''Der Ring des Nibelungen'' by Richard Wagner.