The 32-year-old Spanish striker was rushed to hospital after being hit from behind by Deportivo La Coruna's Alex Bergantinos.
The 32-year-old Spanish striker was rushed to hospital after being hit from behind by Deportivo La Coruna's Alex Bergantinos five minutes before the end of the game.
He hit the ground hard and appeared to have already lost consciousness.
Players from both sides immediately called for urgent medical attention. Distressed Atletico defender Jose Maria Gimenez was seen crying.
Deportivo fans gave the former Spanish international a standing ovation of encouragement as he was stretchered off the field.
But a CT scan revealed Torres suffered no traumatic brain injuries.
And the striker sent out a message on Twitter from his hospital bed just after midnight.
"Thanks to all of you who were worried for me and for your messages of encouragement," Torres said. "It was just a scare. I hope to be back soon."
Atletico also confirmed that no serious damage had apparently been inflicted.
"A cranial and cervical CT scan carried out on Fernando Torres has ruled out that the Rojiblanco striker has suffered any alterations or traumatic injuries," Atletico said in a statement.
"Our player, who is stable, conscious and lucid, had to be removed by ambulance after being stabilised according to the usual protocol, before entering the Model Hospital of La Coruna."
The club said Torres left hospital on Friday. "He will have to observe a 48-hour rest."
Atletico coach Diego Simeone acknowledged the widespread worries over the clash of heads but sought to play down the severity.
"The action was not pretty to watch but these are the events that unfortunately happen during a game. We wish Fernando all the best," Simeone told a press conference after the game ended in a 1-1 draw.
"We are all scared," Atletico left-back Filipe Luis told BeIN Sports.
"The news we have received until now is good. The most important thing is that Fernando is ok."
Atletico's Sime Vrsaljko and captain Gabi have also been praised for reacting quickly to ensure Torres didn't swallow his tongue whilst unconscious.
The visitors had to play out seven minutes of stoppage time with 10 men as they had already made all three substitutions.
Former West Bromwich Albion manager Pepe Mel was making his bow as Deportivo coach after only being hired on Wednesday.
And the hosts made the perfect start when Florin Andone capitalised on a poor goal kick from Jan Oblak to run through and slot past the Slovenian.
Atletico responded after half-time and equalised in stunning fashion 22 minutes from time when Antoine Griezmann thrashed home a shot from fully 30 yards.