West Ham's unbeaten European record was reduced to ruins in Athens as they crashed to a 2-1 Europa League defeat at Olympiacos.
Liverpool manager Jurgen Klopp hailed Ryan Gravenberch's "obvious talent" as the midfielder paved the way for the 2-0 win over Union Saint-Gilloise with his first goal for the club.
Ryan Gravenberch benefited from an error by Union Saint-Gilloise to score his first goal in a 2-0 Europa League win.
West Ham continued their continental cruise as headers from Lucas Paqueta and Nayef Aguerd secured a 2-1 win at Freiburg.
Brighton gave themselves a Europa League lifeline as Joao Pedro's late penalty completed a comeback from two goals down away to Marseille.
Ghana midfielder Mohammed Kudus was delighted with West Ham's winning start to their Europa League campaign.