The club's next entry, into the re-branded UEFA Europa League in 2009 (having lost the previous season's Cup final to Barcelona), involved the setting of new club records, as 16-year-old Iker Muniain became the club's youngest player in a European match in the first leg defeat to Young Boys, then came off the bench and scored the goal which saw Athletic progress on away goals in the return in Switzerland. Despite failing to win at home again in the next round, a long journey north to the Arctic Circle was rewarded with a narrow aggregate victory over Tromsø and qualification to the group stage, where two wins over Austria Wien (the away leg interrupted by a pitch invasion by local right-wing hooligans) were mitigated by a pair of defeats to Werder Bremen (the only German opponent to win in Bilbao). In the first knockout round, Athletic endured their worst aggregate losing margin in a 1–5 reverse to Anderlecht, led by another 16-year-old forward, Romelu Lukaku, while more violent incidents involving supporters occurred at San Mamés in the first leg and in the streets of Brussels prior to the second leg.