Rio 2016: US anti-doping chief hopes IOC will follow CAS decision on Russia ban

America's anti-doping leader renewed the call to ban all Russian athletes from the Rio Olympics after the Court of Arbitration for Sport (CAS) rejected an appeal by Russian athletics competitors on Thursday.

Three days after an investigation report unveiled evidence of a state-run doping scheme in Russia, CAS rejected a Russian appeal of world athletics governing body IAAF's decision to ban all Russian track and field competitors from the Rio Games, which open August 5.

"It's a sad situation for everyone who loves sport, especially those Russian athletes who were abused and harmed by their leader's actions -- but it's the right outcome," US Anti-Doping Agency chief executive Travis Tygart said in a statement. The decision is seen as an indicator to how the International Olympic Committee (IOC) might vote Sunday when its executive board conducts more talks on whether to bar any Russians from competing at Rio.

"We hope ... the IOC will now follow the path this decision has paved and restore faith in the Olympic values by exercising its authority to suspend the Russian Olympic Committee while allowing for a process by which individual Russian athletes can compete if they can prove they are truly clean," Tygart said.

Weighing their responsibility to those who have not tested positive against the potential far-reaching dope cheating range of a state-backed scheme is the problem facing the IOC as it tries to ensure clean athletes a fair Olympic playing field.