Betty White on ‘The Tonight Show,' Shaq takes on Dale Earnhardt Jr. on ABC

Turns out "Nashville Star" winner Melissa Lawson's life turned into a bit of a mess after the show -- while she was on tour and recording, her husband had an affair. So in the wake of her personal life and career in shambles, Lawson turns to none other than Tony Robbins to help on "Breakthrough With Tony Robbins" (NBC at 8 p.m.).
Chef Gordon Ramsay tests the contestants' senses of flavor when they have to re-create a dish without actually knowing any of the ingredients on "Hell's Kitchen" (Fox at 8), and later, the winning chef gets a day of relaxation, while another has a breakdown in the kitchen.
On the heels of a few shows from Canada doing okay-ish ratings for broadcast networks in the summer, CW premieres Canadian comedy "18 to Life" (at 9 and 9:30), about two 18-year-old neighbors -- with warring families -- who get married after a high-stakes game of Truth or Dare.
Shaquille O'Neal's reality show "Shaq Vs." (ABC at 9) -- in which the NBA superstar challenges other athletes in their own sports -- takes an odd twist in the Season 2 premiere, as Shaq travels to Washington to take on . . . 15-year-old Scripps National Spelling Bee champion Kavya Shivashankar? Sure enough, Shaq tries to expand his horizons with a spelling challenge, and even gets a little help from the champ's sister, 8-year-old Vanya. But first, Shaq tries to squeeze his 7-foot-1, 325-pound frame into a stock car to compete against Dale Earnhardt Jr. in a NASCAR race in North Carolina.
Shark Week continues on Discovery, though anyone taking a beachside vacation in the next few weeks should take caution before watching "Shark Bite Beach" (Discovery at 9), which looks at the attacks along the California and Mexico coasts in 2008.
Season 3 of "The Rachel Zoe Project" (Bravo at 10) kicks off with the stylist's team reeling after Zoe fires her assistant, Taylor; and in the midst of the chaos, everyone must work to get Demi Moore ready for a photo shoot.
A couple of lottery winners mysteriously disappear on "Memphis Beat" (TNT at 10), leaving Dwight to search for the pair before something terrible happens.
Auggie diligently tries to rescue Annie from an uncomfortable situation in Moscow on "Covert Affairs" (USA at 10), not even realizing that his job could be in jeopardy when Joan and Arthur suspect him of not being faithful to the organization.
Actress Betty White stops by "The Tonight Show With Jay Leno" (NBC at 11:35), along with actor Sam Trammell and the Black Crowes.
"Late Show With David Letterman" (CBS at 11:35) has actor Michael Cera, talk-show host Rachel Maddow and musical guest Herbie Hancock.