The Court of Arbitration for Sport (CAS) has opened a full week of appeal hearings for 39 Russian athletes disqualified from the 2014 Sochi Olympics for taking part in a state-backed doping program.
CAS says it expects to give verdicts next week.
Some athletes hope to overturn their Olympic life bans and compete at the PyeongChang Games, which open in South Korea on February 9.
Two key witnesses, Russian whistleblower Grigory Rodchenkov and World Anti-Doping Agency (WADA) investigator Richard McLaren, are set to testify by video or telephone link to the closed-door hearings.
Swiss law firm Schellenberg Wittner is representing the 39 athletes from seven sports, including several gold medallists, before two separate judging panels.
The firm's lawyers say they believe the IOC banned the athletes "despite a lack of specific evidence".
