John Cena retired from professional wrestling on December 13 at Saturday Night's Main Event. He lost his final match to Gunther, but received overwhelming support from all of his colleagues.Cena's former rival and current WWE Superstar, Rusev, has shared the ring with him on several occasions. They also crossed paths on The Grandest Stage of Them All.On social media, Rusev expressed his gratitude to Cena and also shared a backstage photo with the former Undisputed WWE Champion."Thank you, John! Thank you for your teaching, your patience, leadership not just by words but action. Thank you that we fought all over the world and it didn’t matter, who is hurt, how many people are in the building or what part of the world we were in, you went in that ring and performed like it’s your last time. I will never forget that. You are the last real Champ. The reason why i still do what i do is because you taught me how to. I will always tell them how bad i am," Rusev wrote.Check out Rusev's post on Instagram below. View this post on Instagram Instagram PostJohn Cena Sr. believes the finish to his son vs. Gunther should've been differentJohn Cena Sr. wasn't happy with the end to his son's final match against Gunther. In a chat with Bill Apter, he said that he wasn't convinced of his son tapping out.Cena Sr. explained how he personally would've booked the finish to the match."I'm not sure that's a tapout. I wonder if it's the last effort to try to break that hold. That would have been a good deal right there. And then, Gunther would have clutched it even more, and Cena would have blacked out. Period. Without a tapout. So Gunther would have still been the winner by default because Cena couldn't answer the ten-count. It would have been better to go that way than I think the way it kind of went."John Cena has confirmed that he will never return to professional wrestling as an in-ring performer and won't end his retirement.