Justin Doellman beat the buzzer to seal a dramatic 87-86 Euroleague Top 16 victory for Barcelona at big rivals Real Madrid on Thursday.
Doellman was mobbed by his team-mates after settling a tense contest against the defending champions, who led 61-47 in the third quarter but were unable to hold on.
Forward Doellman scored 24 points in an outstanding display in which he was successful with all six attempts at three-pointers before having the final say.
Shane Lawal also grabbed six rebounds as Barca took their record to 2-2, while Sergio Rodriguez's 18-point haul was not enough to prevent Real from suffering a defeat which also ensures they are 2-2.
Barca's Group F Clasico victory came despite the loss of Juan Carlos Navarro to injury.
Laboral Kutxa and CSKA Moscow are also 2-2 in Group F after the Basque side beat the Russian club 81-71.
Ioannis Bourousis conjured up 19 points and took 13 rebounds in an impressive all-round display for the home side, who were backed by a crowd of 11,500.
Lokomotiv Kuban Krasnodar are now second in Group E following a 76-67 home win over Panathinaikos which saw them improve to 3-1.
Dontaye Draper scored a game-high 20 points for Lokomotiv, landing six three-pointers, and Malcolm Delaney added 14 points, as well as coming up with six assists and clutching five rebounds.
Cedevita Zagreb beat Anadolu Efes 84-80 in the other Group E match to leave both sides at 2-2 after round four.