Despite neither man being older than 33 years old, Brazilian stars Antonio Rodrigo Nogueira and Wanderlei Silva have faced recent doubts about how much they have left in their respective gas tanks as they continue the chase for UFC gold.
The questions stem not from their age, but from the physical styles that have made them among the most successful and legendary fighters in MMA's short history.
But ask either man about the idea that next Saturday's UFC 110 bouts pitting Nogueira against Cain Velasquez and Silva against Michael Bisping represents a battle of old veterans against rising youngsters, and you'll meet some resistance.
"For who calls me old, I'm very mad at them," Nogueira said with a chuckle during a recent teleconference. "We come from different generations. Of course, we had time in Japan, and then we came to America very hungry. We want our place here, too."
Nogueira is arguably one of the top two or three heavyweights of all time, and has been in or around the title picture of every promotion he's fought in for most of his career.
At 31-5-1, the 33-year-old has beaten scores of big names. And while it seems as though a record like that shouldn't need to be defended, some critics came out of the woodwork after Nogueira was stopped for the first time in his career against Frank Mir at UFC 92.
After taking some time off, he rebounded with a solid win over Randy Couture at UFC 102, and now will have to defeat the rising Velasquez -- a cardio and wrestling machine -- to get back in the title hunt one more time.
"We're still very good fighters," Nogueira said. "We can see the new, upcoming guys. We respect them a lot. They're good opponents. It doesn't matter where they come from or when they start to fight, they're very good opponents. We're going to pick our level up when we fight the best guys in weight division. That's how we're going to fight."
Silva, meanwhile, has had a much more rocky road as of late, losing five of his last six dating back to Sept. 2006, including three knockouts. That's dropped his career mark to 32-10-1 with one no contest.
He hopes the fight with Bisping will mark the beginning of a new phase in his career. It is his first time competing in the 185-pound division, where in theory the punchers are not quite so powerful. The hope is that his power will mean more in a weight class with smaller men.
"He doesn't have a lot of experience, but we come from different times in the life of MMA," Silva said of Bisping. "For me it's a good experience and I'm going to give a great show in Sydney."
Not surprisingly, both Velasquez and Bisping have been quite respectful of the two pioneers now standing in their respective paths.
"Wanderlei and Nogueira have been around long, long time," Bisping said. "I grew up -- when I first got into MMA -- watching their fights in PRIDE. So for me, it's a great honor to be fighting Wanderlei. I'm not sure it's a different generation, but they've been at the forefront of MMA a lot longer than people like myself and Cain. It's an honor to be fighting him."