Koke's sixth-minute winner sent Atlético Madrid through to their first European semi-final in 40 years at the expense of Barcelona in the Champions League on Wednesday night.
Atléti and Barça had drawn all four of their previous encounters this campaign, but Koke - billed by Xavi as his heir in the Spanish national side - finally separated the teams on one of the most memorable nights at the Vicente Calderón.
Coach Diego Simeone continued to work wonders at Atléti even without influential top scorer Diego Costa, as David Villa revelled in his favoured central striker role. Atletico hit the woodwork three times during their early burst and wasted several other chances late on.
Barça, experiencing their most turbulent season since Frank Rijkaard's fractious final seasons, could still end the campaign successfully. They trail Atléti in the Primera Liga by just a point with six games remaining and entertain the league leaders on the final day of the season.
The Blaugrana also play Real Madrid in the Copa del Rey final next week.