Celtic threw away a two-goal lead and lost 4-3 to Real Betis in a pulsating start to the group stage of the Europa League, while West Ham celebrated a 2-0 win against Dinamo Zagreb.
Eighteen years after reaching the UEFA Cup final in Seville, Celtic returned to Andalusia and made a dream start at the Benito Villamarin.
Albian Ajeti bundled the opener home thanks to a VAR check after scoring the goal initially for the Handball had been excluded.
The Swiss striker was then knocked down in the penalty area by Claudio Bravo and Josip Juranovic buried his first Celtic goal from the penalty spot.
But the defensive weaknesses that the early days of Ange Postecoglou as the person responsible of the Glasgow giants, the guests cost a decisive victory.