UEFA Europa League – Semi-finals (First Leg)

3 May 2017
Ajax Amsterdam – Olympique Lyonnais
Referee: Gianluca Rocchi (ITA, photo)
Assistant Referee 1: Elenito Di Liberatore (ITA)
Assistant Referee 2: Mauro Tonolini (ITA)
Additional AR 1: Luca Banti (ITA)
Additional AR 2: Paolo Valeri (ITA)
Fourth Official: Filippo Meli (ITA)
Referee Observer: Alexandru Deaconu (ROU)

4 May 2017
Celta Vigo – Manchester United
Referee: Sergey Karasev (RUS)
Assistant Referee 1: Anton Averianov (RUS)
Assistant Referee 2: Tikhon Kalugin (RUS)
Additional AR 1: Sergey Lapochkin (RUS)
Additional AR 2: Sergey Ivanov (RUS)
Fourth Official: Igor Demeshko (RUS)
Referee Observer: Alfredo Trentalange (ITA)