Scott McTominay has revealed he received treatment to correct an irregular heartbeat two days before Scotland's World Cup win over Haiti in June.
The Napoli midfielder recently underwent an ablation procedure - a minimally invasive operation to correct irregular heart rhythms - in Manchester.
At the World Cup, the 29-year-old was was put to sleep to correct his heartbeat and was given the all clear to play in the opening 1-0 victory over Haiti in Massachusettes.
"I had to go and get the shock on my heart," the former Manchester United player, who also also played the 90 minutes in the losses to Morocco and Brazil, said.
"I was two days before the Haiti game. You've prepared so well. I was in such good condition and then something like that happens. You're thinking, 'how is this happening to me'?
"You have to get on with it, that's the cards that you're dealt in football. Sometimes, things don't go your way.
"I was 100% [fit], but obviously, whenever you're sat in a hospital bed two days before the first game of the World Cup about to get put to sleep, it's not ideal, is it?"
McTominay praised his club and the medical staff who treated him in the autumn.
He missed Scotland's opening four Nations League fixtures - a win, a draw and two defeats - but has been recalled to the squad after returning to domestic and European action with Napoli.
Sebastien Pocognoli's Scots host North Macedonia on Friday and visit Switzerland on Monday.
"Yeah, I'm good," McTominay said. "I'm feeling much, much better than what I was. I feel like it was something that needed to be done. In your career, you have moments like that where things can take you a bit by surprise.
"Obviously, it looks a lot worse to people in the media and family and friends who reach out to you after they see news related to a heart issue, but it's a relatively straightforward procedure, which went really, really well in Manchester.
"So just really happy to be back and playing football again. That's the most important thing in my life and it always will be in terms of wanting to come back and prove myself again and making sure that I can go to another level."
Nations League: Scotland v North Macedonia
McTominay added: "For me, it's always about coming back stronger.
"No matter how well you play in one game, it's about the next game and pushing yourself and recovering well and eating the right things, sleeping correctly throughout your career."
