The clash of heads reverberated around the stadium, everyone watching feared the worse, but Fernando Torres was only looking forward to getting back to training on Friday.
The 32-year-old Spanish striker was rushed to hospital unconscious after being hit from behind by Deportivo La Coruna's Alex Bergantinos five minutes before the end of the game.
But after a night's rest and with serious injury ruled out, Torres left hospital again Friday and sought to reassure fans.
"Everything is fine and fortunately, in a few days, I will be able to train with the others again," Torres told reporters.
The former World Cup winner told how he remembered what happened just before the blow and how he recovered consciousness in the ambulance heading to the hospital.
"Thank God, it was not serious," Torres said, adding how Bergantinos had gone to his hospital bed.
"Yesterday I was with Alex. He was worried but these are things that happen in football and can happen to anyone.
"By luck it was just a scare and now I am counting the days to getting back to training."
Torres gave his team a mighty scare however.
Players from both sides immediately called for urgent medical attention when he slumped to the ground unconscious.
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.
But the striker sent out a Twitter message from his hospital bed just after midnight and the club also said there was no apparent serious injury.
"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."
"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.
- Not pretty -
The club said that after leaving hospital, Torres would 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 after the game.
Atletico's Sime Vrsaljko and captain Gabi have been praised for reacting quickly to ensure Torres did not 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 equalised in stunning fashion 22 minutes from time when Antoine Griezmann thrashed home a 30-yard shot.