The heavyweight division never ages. That much is clear when you consider in 2015, over a decade after they first staked their claims as UFC champions, Frank Mir and Andrei Arlovski are about to meet each other at UFC 191 with genuine title implications on the line. No matter how many times you read it, that sentence will never cease being strange.

For Mir, the circumstances that led to this point were unexpected in two separate ways. Most obviously, Mir was all but assumed to be done last year once Alistair Overeem painted him 10 shades of dark crimson in the defining moment of a career-worst four-fight losing streak. But for a reason more timely, Mir simply didn't expect to be asked back on such a quick turnaround after slaying Todd Duffee last month with the mother of all punches.

"Actually, I was (surprised)," Mir admitted Thursday on a UFC 191 media conference call. "I got the call just a few days after my fight and was asked if I would contribute to the already great card coming on Labor Day weekend. It would help the card overall, so I stepped up to the opportunity they presented me."

If Mir was caught off guard by the UFC's scheduling request, he was even more thunderstruck once he realized who matchmakers actually wanted him to fight.

Even counting Mir's resurgence, Arlovski is perhaps the most incredible feel-good story to emerge out of the UFC this decade. "The Pitbull" has defied both expectations and Mother Nature by rampaging his way to a No. 4 ranking, led in large part by his electrifying knockout over perennial contender Travis Browne at UFC 187.

The opportunity to thrust Arlovski into a title shot seemed almost too perfect of a match-up to kickstart the heavyweight division in a post-Velasquez world. And even Mir was shocked when the UFC passed it up in favor of booking an immediate rematch between Velasquez and the man who trounced him, Fabricio Werdum.

"I thought that actually it mixed up the division by having [Werdum] take over as the champion," Mir said. "I thought Andrei was actually going to get the title shot, and I thought that was extremely interesting. But for Cain to get the immediate rematch, the guy is a great champion so I guess you give him that opportunity.

"A lot of people want to put it to the oxygen was very thin there, and I don't know. I wasn't in Cain's training camp, I don't know how much that really contributed to it. I know that Fabricio was fighting in [elevation], so I think that Fabricio just really had a great night."

Mir's surprise is even more understandable considering that had the UFC gone the route of Werdum vs. Arlovski, an outside chance existed that if both Mir and Arlovski won their next fight, their match-up more than 10 years in the making could've been held for an actual UFC belt -- something that seemed preposterous as recent as a year ago.

Mir can't help but look at the missed chance there, even if he's grateful for the opportunity against a top contender.

"Andrei is right, it is just business," Mir said. "That's the next fight they wanted me to go and fight. Obviously I admit that I would rather have had more time. I thought that maybe this fight had so much history behind it, that maybe a build-up longer than six weeks would've been better for us.

"At the same time, I think both of us represent so many of the same great qualities of persevering through adversity. I would've liked it if one of us had the title and the other one came up and was the one who challenged so many years later. I think when you write the story at the end of our lives, that would've been a much more interesting read than just kind of hurried, rushed, let's fight each other now, with both of us right now at this point of our success."

Still, it's not as if Mir is disappointed by how things worked out. A win over his old friend Arlovski would throw Mir within shouting distance of a title shot -- a fitting end considering 2015 appears to the golden year for heavyweight's old guard.

"I think this era right now is the best it's ever been," Mir said. "I think in the past, we've always had top-level guys, but I think it dwindled off after four or five. Right now there are guys who are (ranked) 12, 13, 14 who are great fighters in the heavyweight division. So I think the top-10 right now is extremely stacked and I think it's the most stacked it's ever been."