Defending champions Liverpool have lost the opening match of their new Champions League campaign.
The Reds went down 2-0 to Napoli on Tuesday night as Dries Mertens and Fernando Llorente scored late goals for the Italian side.
Elsewhere, Marc-Andre ter Stegen saved a penalty as Barcelona held Borussia Dortmund to a goalless draw.
Chelsea's return to the Champions League saw Valencia claim a 1-0 victory at Stamford Bridge.

England beat New Zealand to keep Pakistan's T20 World Cup hopes alive
Medvedev to face Griekspoor in bid for second Dubai title
Real Madrid face Man City again in Champions League knockouts
India defeat Zimbabwe to revive T20 World Cup hopes
Auger-Aliassime sets Medvedev semifinal in Dubai