The Undertaker has been the greatest at so many things when it comes to life as a professional wrestler, and his ability to not break character outside of the ring is certainly one of The Deadman's better qualities.

But this time, Undertaker was seen completely breaking character by donning Rey Mysterio merchandise while posing in a photo with his wife, Michelle McCool. The Master of the 619 shared the post on his Instagram page.

It's a great sign of respect from The Undertaker, who had no problem breaking character and thus sending social media into a frenzy. It just goes to show how much he and Rey Mysterio, both future Hall of Famers, respect another after spending over a decade together in the WWE.

Another interesting thing to note here is The Undertaker dying his beard black, a hint that perhaps he's set to return to the ring soon. The SummerSlam pay-per-view is only 10 days away now, so might we see his first appearance on WWE programming since the Greatest Royal Rumble?

As for Mysterio, he's been in well-documented contract negotiations with the WWE over the past eight months or so, and made appearances at the Royal Rumble and Greatest Royal Rumble this year.

In a recent interview with the Miami Herald, Mysterio revealed that the two sides continue to talk, but "It’s still up in the air," and  "Nothing secure, yet." It sounds like it's only a matter of time until he re-signs with the company, however.

Even though both 'Taker and Mysterio have spent the bulk of their respective careers on the SmackDown brand, the two were rarely used together in storyline. Mysterio did face The Deadman in a losing effort for his World Heavyweight Championship on the May 28, 2010 episode of SmackDown.

It's great to see that the two sides have maintained their close relationship, even though they haven't worked together in the WWE for some years.

NEXT: VINCE MCMAHON'S ADVICE TO RONDA ROUSEY BEFORE WRESTLEMANIA WAS PERFECT