Julian Alvarez opened the scoring for Atletico early on as Diego Simeone's side boosted their chances of a top-eight finish following a mixed start to the league phase, AFP reported.
Piotr Zielinski levelled in the second half for Inter but the visitors faded in the final stages and Atletico capitalised.
Gimenez headed home Antoine Griezmann's corner to claim a potentially vital triumph for the Rojiblancos at a rocking Metropolitano stadium, according to AFP.