It comes with CAS and the Olympic movement dealing with a major state-run doping controversy involving Russia that threatens to overshadow the August 5th-21st Games.
CAS opened two temporary offices in Rio on Tuesday and they will operate for the duration of the Olympics, for what promises to be a busy time for the court as Russian competitors learn whether sports federations will allow them to take part.
Russia's four-time world breaststroke champion Yulia Efimova plans to appeal her ban at CAS, which has already ruled in favour of a blanket ban on the Russian track and field team over doping.
"For the first time in the history of the Olympic Games, the CAS will be in charge of doping-related matters arising on the occasion of the Games as a first-instance authority," CAS said in a statement.