The Spain international striker scored twice in three first-half minutes as Atletico cut the gap to leaders Barcelona back to 7 points.
Madrid: Alvaro Morata's first-half double fired 10-man Atletico Madrid to a 2-0 victory at Real Sociedad as Diego Simeone's men kept their slim La Liga title hopes alive.
The Spain international striker scored twice in three first-half minutes on Sunday as Atletico cut the gap to leaders Barcelona back to seven points after the reigning champions' 1-0 Clasico win over third-placed Real Madrid on Saturday.
Midfielder Koke was dismissed just after the hour mark, but Atletico have now won three straight league games after back-to-back defeats by Real Betis and Real Madrid last month had ended an 18-match unbeaten run.
"The sending off of Koke ended the game as we had planned it," said Atletico coach Simeone.
"We had to defend, make ourselves strong in our penalty area and take a game that was very important to win." After a slow start to the contest, Morata gave Atletico the lead on the half-hour mark by nodding home after Thomas Lemar's corner was flicked on by Diego Godin.
The 26-year-old, who went four games without a goal after joining on loan from Chelsea in January, made it three in two matches shortly afterwards, having opened his Atletico account last weekend against Villarreal.
Once again it was a set-piece that did the damage, as Morata climbed highest to meet Koke's right-wing free-kick with a downward header into the bottom corner.
Sandro Ramirez nodded over as Sociedad started the second half strongly, and the hosts were given renewed hope when Koke was sent off for a second yellow card in the 62nd minute.
Mikel Merino came close to halving the deficit with 14 minutes remaining as away goalkeeper Jan Oblak had to produce a fine save to prevent his header from finding the top corner.
But Atletico closed out the win to move five points clear of city rivals Real, and more importantly, remain in with a chance of lifting a first major trophy since winning the league title in 2014.