REAL Sports with Bryant Gumbel

WADA: "Real Sports" investigates allegations that the World Anti-Doping Agency, or WADA, is failing to adequately police international sport for the use of performance-enhancing drugs. Insiders claim that WADA's mission is being compromised by conflicts of interest and outside meddling. Correspondent Jon Frankel reports. Producer: Max Gershberg.

DARREN WALLER: Battling drug addiction at the start of his NFL career, Darren Waller was suspended from the league and almost died from a drug overdose. After a fresh start with the Raiders, Waller miraculously turned his career around, becoming one of the league's top tight ends. Now, he's also putting in the work off the field, partnering with his drug sponsor to help save other addicts, by pulling them from the underground tunnels beneath the Las Vegas strip. Correspondent David Scott reports. Producer: Evan Burgos.

FRANCES TIAFOE (Update): "Real Sports" first profiled then-rising US tennis star Frances Tiafoe in 2017. The revealing segment showed how unlikely and remarkable his backstory was in a sport that typically has a high barrier to entry. Now, after beating all-time great Rafael Nadal on his way to becoming the first American in 16 years to make it to the semifinals at the US Open, Tiafoe is one of the most talked-about stars on the court today. Correspondent Mary Carillo reports. Producers: Beret Remak, Hannah Vicente-Kliot.