The Swiss referee Sandro Schärer will officiate Atalanta-Olympiacos, the first leg of the 2021-2022 UEFA Europa League knockout round playoffs. His assistants will be Stephane De Almeida (SUI) and Jonas Erni (SUI), fourth official: Alessandro Dudic (SUI), V.A.R. Marco Fritz (GER), A.V.A.R. Fedayi San (SUI).
