Palmeiras controlled the first leg, finishing with 63 per cent of the possession while Athletico scored from their only shot on target, so when Gustavo Scarpa equalised on aggregate less than three minutes into the second leg, it appeared the reigning back-to-back champions would run away with the tie.
With 11 shots to three in the first half, it was all Palmeiras in front of their home fans – until a VAR review deemed centre-back Murilo Cerqueira's challenge worthy of a straight red card.
Everything changed after half-time, as it was now Athletico controlling 62 per cent of the ball and dictating play, but in the 55th minute Palmeiras took control as Gustavo Gomez found the back of the net to make it 2-0, and 2-1 on aggregate.
Needing goals, Athletico subbed on Pablo, who paid immediate dividends when he scored one minute after his arrival in the 64th minute.
Pablo then turned distributor for the decisive strike, finding David Terans in the 85th minute to stick a dagger into home fans and secure the 3-2 aggregate victory.
It will be Athletico's first appearance in the final since 2005, where they lost to Sao Paulo.