While both men have been involved in some great feuds over the years, the rivalry between CM Punk and Rey Mysterio in WWE is one of the most underrated in both of their careers.

The rivalry spawned three PPV matches, with all three bouts holding interesting stipulations, but it wasn't just the actual matches that made this feud so great. The storytelling was just absolute top-notch from both men.

RELATED: CM Punk's Career Told In Photos, Through The Years

The promos were incredible, and it was the scariest Punk had ever looked throughout his WWE run. The Straight Edge Society gimmick was finding its feet, and Rey was the perfect underdog adversary to stand up against the crazy cult in order to protect his family.

In the grand scheme of things, both men have taken part in feuds that were much more appreciated, and talked about than this one, but it deserves a lot of love and is easily one of the best that both men have had throughout their careers.

It Was Punk At His Evil Best

Having turned heel in WWE for the very first time earlier in the year, and on the back of a truly incredible feud with Jeff Hardy, Punk formed the Straight Edge Society in late 2009, and it quickly solidified his role as a truly tremendous villain.

He turned on fans, and preached his straight-edge lifestyle, initiating several members into the group which included Luke Gallows and Serena Deeb. The stable went on to be one of the most entertaining in WWE, and Punk was firing on all cylinders as the evil cult leader.

via fanpop.com
via fanpop.com

Facing off with the ultimate underdog in Mysterio was a perfect move, and it just helped solidify just how great a villain the two-time Money in the Bank winner had become. Punk was twisted, but it worked because it was clear there was a genuine lick of truth to what he was saying. He believed in his gimmick, and it helped create one of the most intriguing characters on WWE television in years.

The Promos Were Incredible

The key to any great wrestling storyline is to find the perfect blend of entertaining matches and excellent promos. There could be some of the greatest matches the industry has ever seen, but without the right storytelling outside of the ring to back it up, a feud can fail to live up to expectations, but that certainly wasn't the case here.

CM Punk Straight Edge Society

The rivalry kick-started after Mysterio eliminated Punk from the Elimination Chamber match, and the promos the two went on to share were incredible and were regularly some of the highlights of WWE television at the time. Who can forget the incredibly creepy moment the Straight Edge Savior interrupted Rey's birthday celebration for his young daughter, with Punk singing happy birthday to the 9-year-old. It was terrifying, but fans were glued to the intense exchanges, and it really helped drill up interest in the eventual matches the two had.

They Had Great Matches

While the buildup is always important in a feud, the eventual matches are vital to ensure it doesn't leave fans disappointed, and the pair put on several great matches throughout the rivalry.

Starting with WrestleMania 26, Punk and Mysterio squared off on three different PPVs, and it was a true testament to just how great the pair was that they managed to get the most out of each match, including the six minutes they had at Mania, and have fans just as invested for the third match as they were the first.

Mysterio v Punk

With stipulations added to all three bouts, the feud was given extra stakes, and it certainly helped push it to the next level. The culmination of a feud should always feel like the most important match though, and that was the case here as WWE combined the two previous stipulations used in their earlier matches, and added them to the final face-off. If Rey lost he would be forced to join Punk's Straight Edge Society, but if the former Ring of Honor champion lost he would have his head shaved.

RELATED: Rey Mysterio's 10 Most Violent Feuds, Ranked

There was a genuine sense that the match could go either way, and while forcing Mysterio into the stable would have made for more interesting television, instead, Punk lost the bout, and was forced to shave his head, losing the long black hair he had become synonymous with throughout his WWE tenure.

While it wasn't portrayed as a main event-level feud in WWE at the time, it was certainly one of the best in the promotion and is easily one of the most underrated of the last two decades, maybe even more.