However, the multiple-time Lightweight World Champion never experienced anything quite as scary as his first bout in ONE Championship.
Alvarez, who returns to battle Saygid "Dagi" Guseyn Arslanaliev in the ONE Lightweight World Grand Prix Championship Final at ONE: CENTURY PART I in Tokyo, Japan on Sunday, 13 October, had a debut he will never forget for all the wrong reasons.
During that exchange, Alvarez suffered a lacerating eye injury, which completely shifted his focus from winning to surviving.
"The eyelid -- both the top and bottom -- split in half," the 35-year-old recalls.
"It was like my eye was split right in half, so I felt air coming into my eye. There was never a time in a fight, no matter how much damage I took, where I stopped caring about the result of the fight.
"That night, in particular, I just felt like my health and safety was at risk. As soon as I got hit, my mind immediately went to, 'I need to get somewhere quickly and whatever damage I took, I need to get it fixed if I want to have any chance to continue fighting for a longer period of time.'"
Alvarez has suffered his fair share of injuries throughout the years, and he remembers each and every one. While the superficial cut was initially horrifying, he is glad it was not something as serious as a knee injury, which could have sidelined him for an extended period of time.
"I still had my legs and arms. My shoulders were good. It was just an eye," he explains.
"I could run and swim, and I could even move around and shadow box. Considering injuries, it wasn't really a bad one.
"I still have 20/20 vision. I don't have anything that's long term. It was just a temporary thing. I always try to look at the brighter side of things."
That attitude has carried Alvarez through every rough spot in his career, which is why he has always been able to recover and come back even stronger.
He never allows himself to get dejected about any particular setback because the next contest will offer a chance at redemption.
"I consider myself a champion, with or without a belt. I hold myself to a higher standard," Alvarez says.
"I wake up in the morning, and I have a standard and I have goals that I want to achieve. I'm responsible, I'm accountable, and I hold myself to that standard of being a champion.
"Champions don't lose often. Champions lose and when you're fighting the best in the world, you're going to deal with losses, but you're not going to lose often. That's the way I live my life. I can't promise I'm going to win every time. But just the type of person I am, I won't lose often."
Despite the stinging defeat to Nastyukhin, Alvarez maintained a positive outlook.
The Philadelphia resident carried that mentality into training camp ahead of his battle with former ONE Lightweight World Champion Eduard "Landslide" Folayang.
He had previously made some valuable improvements to his skill set, and he was determined to showcase them in his next match-up.
"The Timofey loss was disappointing to me because I spent four or five months preparing, and I had gotten so much better," he explains.
"I cleaned up a lot of bad habits. My footwork got better. A lot of things got better. So what I did when I lost to Timofey, instead of getting down and losing that momentum, I just focused on how much better I got as a fighter.
"I'm not going to define my career on one performance on one single night in a couple of minutes. I'm not going to let it slow me down."
Alvarez backed up that statement when he stood toe-to-toe with Folayang at ONE: DAWN OF HEROES inside the Mall Of Asia Arena in Manila, Philippines last month.
This bout was dramatic too, as the Filipino's thunderous leg kicks caused the "The Underground King" to fall onto the canvas nearly 90 seconds into the contest.
Folayang followed him to the mat and unleashed his ground strikes, but the American remained calm. That calmness allowed him to sweep his rival, take his back, and submit him via rear-naked choke.
"It was a typical 'Underground King' fight," Alvarez says.
"Get beat up a little bit, deal with some serious damage and adversity, and then find my way back, stay focused, and then find a way to win."
Now, Alvarez is focused on finding a way to defeat Arslanaliev at ONE: CENTURY PART I.
If he succeeds, he will become the ONE Lightweight World Grand Prix Champion and receive a shot at reigning ONE Lightweight World Champion Christian "The Warrior" Lee.
That would be a dream come true for "The Underground King," and undoubtedly his finest moment in The Home Of Martial Arts.