When Sin Cara signed with the WWE in 2011, just about everyone expected the popular luchador to cross paths with the company's resident high-flyer, Rey Mysterio.
Roughly a year-and-a-half later, it's finally happening.
Though they may not be an official tag team just yet, Mysterio and Sin Cara have been teaming up quite a bit recently and look poised to become a full-time tag team in the immediate future.
While the two aerial artists might be getting along right now, however, it seems like a damn near guarantee that they will wind up facing each other one on one in a highly anticipated battle between the two most popular Hispanic wrestlers on the planet.
Here are seven reasons why Rey Mysterio vs. Sin Cara is inevitable.
How many times does a ridiculously easy storyline just fall into the WWE's lap?
Well, not all that often.
It's rare that the WWE has two performers who fit so perfectly together that a feud between the two requires almost no work whatsoever to book.
But that's exactly what the WWE has with Rey Mysterio and Sin Cara.
You've got the "old" luchador mentoring the young luchador who mirrors himself in so many ways. At first, they work together, but eventually, a rivalry develops between the two.
Ultimately, the two will step into the ring for a one-on-one battle to determine who is the WWE's top Hispanic superstar and its No. 1 high-flyer.
It doesn't take a genius to write this one. The story writes itself.
And since the WWE has a potentially great storyline between Mysterio and Sin Cara creating itself, it's highly unlikely that it won't happen.
I'm sure you've read this rumor at some point or another.
According to F4WOnline.com (via WrestlingInc.com), the WWE originally planned to have Rey Mysterio take on Sin Cara at WrestleMania 28 earlier this year.
Unfortunately, those plans fells through when both Mysterio and Sin Cara suffered very serious injuries in 2011 and neither was healthy enough to compete at the biggest pay-per-view of the year.
Since Mysterio vs. Sin Cara didn't happen then, I think that almost guarantees that it will happen down the road.
The WWE desperately wanted to put its top two high-flyers in a match on the grandest stage of them all, but due to circumstances beyond the company's control, the match wasn't able to come to fruition.
But that doesn't mean that the WWE just threw the plans for Mysterio vs. Sin Cara in the trash.
If anything, those plans were just put on hold.
Sin Cara hasn't had a great WWE career so far.
Upon his arrival to the company, he quickly developed a reputation as a botch artist. He then got himself suspended for violating the Talent Wellness Program and he suffered a major injury that kept him off of TV for more than half a year.
By all standards, Sin Cara has been a major disappointment, especially when you consider the high expectations the WWE had of him when he debuted.
Yet, through it all, the WWE has remained committed to making Sin Cara a star.
They've stuck with him through thick and thin, and they're doing anything and everything in their power to help him get over and become a huge star in the company.
If Sin Cara can botch up a storm, get suspended, get injured and still have the WWE's support, then the company is obviously willing to do a lot to help him out.
And the one thing that would help Sin Cara the most? A program with the guy he's most often compared to: Rey Mysterio.
The WWE has shown the willingness to make Sin Cara succeed, and nothing will do that better than putting him against the Master of the 619.
Rey Mysterio doesn't have a ton of time left.
He's been wrestling for more than 20 years, is nearing 40 years old and has had more knee operations than I care to count.
Like him or not, Mysterio is going to leave a gaping hole in the WWE when he retires, which could come at some point within the next few years.
But that hole might not be so big if the WWE builds someone up to "take Mysterio's place" when he's gone.
That's where Sin Cara comes in.
Though he will never be "the next Mysterio," Sin Cara is going to be the closest thing we'll see to Mysterio for a long time, and the WWE will undoubtedly want him to essentially fill Mysterio's spot whenever Mysterio is ready to hang up his boots.
In other words, Mysterio will "pass the torch" to Sin Cara when his days as a wrestler over.
But if that's going to truly happen, then it will have to happen by having these two high-flyers go one on one in a potentially epic match before it's too late.
For all intents and purposes, Rey Mysterio and Sin Cara are now a tag team.
Yeah, they haven't been teaming together for more than a few weeks, and they don't have an official team name, but it's very clear that they're going to be an official tag team in the near future.
Keeping that in mind, let me ask you a question: What do almost all tag teams do?
They break up.
We've seen it happen hundreds of times. Two guys team together and something happens that pisses one of them off. They start fighting, they feud, they have a match and then they go their separate ways.
If this Sin Cara/Mysterio pairing lasts for any substantial amount of time, then that's exactly what's going to happen to these two as well.
We may not see one of them turn heel, but I'd bet my bottom dollar that we'll see them split and face each other in a huge match down the road.
History tells us so.
Remember how Sin Cara and Rey Mysterio were reportedly supposed to wrestle each other at WrestleMania 28 but didn't?
Well, as you may have expected, the WWE is already in the process of trying to make that match happen again.
According to PWInsider.com (via SEScoops.com), the current plan is for the tag team of Sin Cara and Mysterio to get involved in the WWE Tag Team Championship picture this fall, eventually split up and go on to face each other at WrestleMania 29.
Plans always change in the WWE, but it wouldn't surprise me in the least if this was true.
The WWE already wanted to have Mysterio vs. Sin Cara once, but the dominoes fell the wrong way and didn't allow it to happen.
Clearly, the company was going to have a redo at some point, and by the looks of things, the seeds are already being planted for it.
Rey Mysterio has faced just about every major star in the WWE.
He's stepped into the ring with John Cena, CM Punk, Randy Orton and the vast majority of the biggest active names in the industry.
At this point in his career, there may be only one match that Mysterio has never had that could be one of his most anticipated bouts ever: a match against Sin Cara.
It would be a battle between the two most well-known Hispanic wrestlers on the planet whose in-ring styles resemble each other so closely.
As noted before, it's an easy story to tell, with Mysterio "passing the torch" so to speak to Sin Cara, who many think will be the WWE's next great luchador and Hispanic superstar.
The story, the stars and the selling points all combine to make Mysterio vs. Sin Cara a major rivalry that would trump anything else that these two could possibly do in the future.
We could see something similar to Sheamus vs. Mysterio or Sin Cara vs. Dolph Ziggler countess times down the road.
But once Mysterio retires, we'll never be able to see anything like Mysterio vs. Sin Cara ever again.
Drake Oz is a WWE Featured Columnist for Bleacher Report. Follow him on Twitter!