As the Ghanaian midfielder rejoiced, his compatriot was left red-faced as he was sent off for a second yellow card offence.
Partey came off the bench on 72 minutes for Jose Maria Gimenez with Atletico leading 3-0 via a first-half brace from Kevin Gameiro and a Saul strike.
He rewarded coach Diego Simeone with his goal following a quick one-two with Angel Correa to shoot low into the net and send his side up 4-0 on 72 minutes before Fernando Torres came on to score the fifth.
Moments earlier, Boateng had been shown a second yellow card for raising his arm during an aerial contest that left defender Gimenez sprawling on the floor.
The 30-year-old striker was magnanimous as he helped the defender back up to his feet before exiting the pitch to the sound of applause from the home crowd.
This incident came a day after Boateng extended his stay with the club where he has enjoyed personal success since scoring 10 goals in his first season, his best ever goals haul.
With his goal, Partey would hope it encourages coach Simeone to give him more responsibility ahead of their Uefa Champions League semi-final game with rivals Real Madrid.