When AZ Alkmaar fans heard their team would be facing Italian giants Napoli in the Europa League with 13 players ruled out because of positive coronavirus tests, they must have feared the worst.
Instead, a side featuring a number of youth teams players pulled off a shock by winning 1-0 in the Group F match.
Dani de Wit curled in the unexpected winner in the second half.
It was a frustrating evening for the hosts, who had dominated throughout.
Elsewhere, Pablo Alcacer scored two goals in just eight minutes after coming off the bench as Villarreal beat Sivasspor 5-3 in a thriller.
Turkish side Sivasspor had come back from two goals down to level 2-2 and although on-loan Tottenham defender Juan Foyth restored the lead for Villarreal, Max Gradel struck to level again for the visitors.
However, Alcacer was introduced in the 70th minute and scored in the 74th and 78th minutes to give the Spanish side victory in Group I.
Mario Gotze made it two goals in two games for PSV Eindhoven but it was not enough to prevent the Dutch side from losing to Granada in their Group E opener.
Gotze had opened the scoring on the stroke of half-time but goals from Jorge Molina and Darwin Machis ensured the Spanish side marked their Europa League group stage debut with a win.
Former Manchester City midfielder David Silva made his 101st European appearance as he helped Real Sociedad beat Croatians Rijeka in Group F.
Silva's clever reverse ball sent Mikel Merino away on the left and his cutback was fired home in stoppage time by Jon Bautista to give the Spanish side victory.
Finally, Bayer Leverkusen were the round's highest scorers as the Germans thrashed French side Nice 6-2 in Group C while Italians Roma came back from a goal down to beat Swiss side Young Boys 2-1 in Group A.