Racing Club was a 2-1 winner at Boca Juniors after playing out the remaining 34 minutes of their Argentine Primera Division fixture.
Boca's home clash against Racing was suspended on 14 September due to torrential rain with Rodolfo Arruabarrena's men leading 1-0 after 56 minutes.
The top-flight fixture was rescheduled to Friday (AEST) and Boca was stunned as striker Gustavo Bou bagged a quick-fire brace for Racing at La Bombonera.
Boca went into the match with a one-goal lead thanks to Jonathan Calleri's opener almost a fortnight ago.
But Racing flourished in perfect conditions in Buenos Aires thanks to Bou, who fired home a half-volley to equalise five minutes after the restart.
Bou was at it again nine minutes later, glancing a header past Boca goalkeeper Agustin Orion - taking his tally to three goals in less than a week.
The defeat handed Boca its first loss under coach Arruabarrena and left the club languishing in 11th spot with 10 points.
Racing is three points better off after ending its three-game winless streak, though it is still seven adrift of league leader River Plate.
River was held to a 1-1 draw by Arsenal in Friday's (AEST) rescheduled fixture.
The Argentine giant and Arsenal had their 14 September meeting postponed without a ball being kicked because of heavy rain.
Over a week later and the two teams were forced to share the spoils.
Hugo Nervo gave Arsenal a 50th-minute lead via the penalty spot, but Leonardo Pisculichi hit back within a minute as River secured a draw at the Estadio Julio Humberto Grondona.