The Rojiblancos have one foot in the round of 16 following a 4-1 away triumph in the round of 32 first leg fixture at Parken Stadium.
Goals from Saul Niguez, Kevin Gameiro, Antoine Griezmann and Vitolo put Diego Simeone's outfit in a commanding lead.
"We came out very plugged, but it was a good job for the whole team and we are satisfied with the win," Partey said, as reported by Football Ghana.
"They started strong, they scored, but we started even better and we knew we were going to come back and the team responded. We are happy.
"It's cold, but we tried to run and so we did not get cold. We went well, we played as we should, and in the end it is winning [that matters] and we have achieved it.
"Before Saul's goal, we had three chances and we did not score. We knew the goal would come.
"Atleti knows how to play, although it also depends on the opponent. When it gets complicated, we look for more in the long run."
Partey lasted for the entire duration of Thursday's match.
Atletico are playing in the Europa League after being demoted from the Champions League.