7 P.M. (USA) UNITED STATES OPEN Venus and Serena Williams will play back-to-back matches following the opening-night festivities, which will celebrate the 50th anniversary of Althea Gibson’s historic victory at what was then called the National Championships. During the ceremony, titled “Breaking Barriers,” African-American female pioneers in the fields of sports, entertainment, politics and the arts will converge on the court to celebrate Gibson’s life and career. Serena Williams, above, was the first black woman since Gibson to win the United States Open; Venus Williams was the first black woman since Gibson to win Wimbledon. Tonight Serena is scheduled to play Angelique Kerber of Germany and Venus will play a qualifier. For Venus this year’s tournament is about more than tennis; this budding designer will be decked out in an outfit and shoes from her new EleVen label, which is produced in partnership with the retailer Steve & Barry’s. The morning rounds begin at 11.
9 P.M. (ABC) FAT MARCH Having already walked 230 miles, the marchers set out from Millstone, N.J., with $70,000 left for each contestant. But Matt’s knee troubles threaten to take him out of the game, and Will is determined to quit, leaving the other marchers to watch their prize money dwindle before their eyes.
10 P.M. (National Geographic) INSIDE AL QAEDA This special examines the state of the terrorist organization — its evolution, recruitment techniques and increasing foothold around the world — through interviews with the Pakistani president Pervez Musharraf, C.I.A. operatives, victims and those who know the group’s power players.
10 P.M. (Travel) ANTHONY BOURDAIN: NO RESERVATIONS Mr. Bourdain’s friendly nemesis Michael Ruhlman (“The French Laundry Cookbook”) challenges him to sate his culinary cravings “where the real people are.” So Mr. Bourdain, above, high-tails it to Cleveland for a sampling of fried pig ears, pork lardon and Skyline Chili. He also meets up with Harvey Pekar, the author of “American Splendor.”
10 P.M. (Showtime) WEEDS U-Turn sends Nancy to stare into the face of danger. Conrad and Heylia find a new place to grow their wares. And Celia hires a lawyer.
11:35 P.M. (CBS) LATE SHOW WITH DAVID LETTERMAN The indie princess Feist, below, performs. KATHRYN SHATTUCK
