With the clock ticking down, it appeared that Diego Simeone’s side were going to draw for the seventh time in their last nine games.
The Ghanaian, however, expertly whipped a free kick into the top corner in the 92nd minute to seal the three points for the visitors, who remain unbeaten in the league.
Chances were at a premium in a dull contest with Atletico substitute Nicolas Gaitan’s effort from distance the only save of note that Deportivo goalkeeper Costel Pantilimon had to make.
When Atletico talisman Antoine Griezmann was substituted for defender Jose Maria Gimenez with 10 minutes to go, it appeared the visitors had settled for the point, before Partey came to the rescue.
The result cuts the gap between Atletico in third and second-placed Valencia to four points. Barcelona, who host Sevilla in Saturday’s late game, are a point clear at the top.
Deportivo remain two places above the relegation zone in 16th.
(Reporting by Joseph Cassinelli; Editing by Toby Davis)
