The last time Los Rojiblancos recorded a league win was at home to Levante on January 4.
Since then they have drawn once and lost twice, including last week’s derby defeat to city rivals Real Madrid.
This time, it was Angel Correa’s sixth-minute strike that made the difference.
Partey played the whole game and got booked in the 68th minute, his ninth caution of the season.
The 26-year-old Ghana international was at his solid best in midfield though, stringing together 52 accurate passes and 71 touches.
He had a 100% success rate with his aerial duels (four from four) and made one interception, two tackles and three clearances.
A visit to the home of Los Che on Valentine’s Day is next on the agenda for Partey and his teammates.