It’s the next best thing to Rocky vs. Martin Riggs, or maybe Rambo vs. Mad Max.

Continuing the tradition of assembling top-flight action stars of the1980s and ‘90s for his bullets-and-biceps franchise, writer/star Sylvester Stallone needed a screen presence equal to his own to square off against his character Barney Ross in The Expendables 3. So he convinced one of his primary rivals for ‘80s box-office supremacy, Mel Gibson, to play Conrad Stonebanks, a one-time government contractor who harbors hard feelings and a particularly dangerous agenda.

If Gibson had any qualms about portraying the bad guy, it’s impossible to tell, as he was as quick with a quip as his longtime Lethal Weapon role. “I thought Dolph Lundgren was the bad guy, so it's a surprise to me,” Gibson joked at a recent press conference. “And I'm kind of shocked and a little offended. I wanted to be the love interest. But there was no one to love, really.”

As long as there are aging but still imposing action stars for him to throw down with, Stallone is ready to lock and load with the best of them, including franchise newcomers Harrison Ford, Wesley Snipes and Antonio Banderas. “Age is a state of old mind,” Stallone insisted. “It gets to a point where if you get old enough, you forget how old you are, and that's the best thing: then you walk around kind of like in a fog. You really don't know how old you are.”

However, he admitted there may be only so many films left. “After the fifth Expendables, you start wearing Depend-ables,” he joked.

On the development of Gibson’s character as a dark mirror image of Stallone’s:

Sylvester Stallone: I just wrote a guideline, and then Mel came up with the idea – well, you explain.

Mel Gibson: Yeah. I kind of worked on the script a little at night and came in kind of hammered out. And I handed the pages to Sly and Patrick [Hughes, the director]. They looked at it, and said, “Yeah, it's cool.” And it was just a theme of somebody who was subcontracted by his government and then thrown under the bus. A real person.

Stallone: So it had a reality to it. And I think what gave it some heart is he was actually saying something that had some truth, and it was valid. And he was committed to it. And I don't believe he saw himself as the bad guy, which is the key to the whole thing. And then you bring in the aspect of Cain and Abel, and two of the best friends that could become the worst of enemies, because usually when you love something that much, you can also hate it even more because of that schism, that break-up. And he just killed it. In the van, I had some dialogue back and forth with him, and the more he did the scene, the more I realized I shouldn't speak. So I just let him roll. And he was convincing himself, he was convincing me, convincing the audience: “What did you do today, Barney? Who did you kill? Who did you blow up? What makes you holier than thou?”

On their epic mano-a-mano fight sequence:

Stallone: It was good. There were situations in actual sports where two rivals get together, two people that have actually done very well in their own world, and then they say, ‘I wonder how they would go against each other?’ And so when that finally happens, it becomes an event.

Gibson: King Kong versus Godzilla!

Stallone: So contact was made, and you do get hurt. I've looked forward to it, and Mel is a great actor. He's very fast, very strong and it was great being punched by him. Thanks very much, Mel.

Gibson: There was no actual contact. Well, it was kind of like movie sex: You don't actually do it.

Stallone: He's a bald-faced liar!

Gibson: And you're battling arthritis, of course, but it was fun. It was fun being shot full of holes by Sly.

Stallone: That's right. If anyone ever wanted to get turned into Swiss cheese, it was Riggs.

On the absence of a former Expendables player and the press pissing match that appeared to follow:

Stallone: What had happened with Bruce Willis? Oh, things didn't work out and Harrison Ford came along, and that happens in film and casting. And it's just the way it is. It's nothing personal. It's not like it got personal – and I'm sorry it did sound that way, but it was just actors talking, and things move on. And I think Bruce Willis is a great guy, and he does fantastically entertaining films. And when he nails it, he nails it big time. [Opening opposite] Sin City? [Laughs, then imitates Rocky IV’s Ivan Drago] “I must crush you.”

On replacing Willis with the action hero’s action hero:

Stallone: Oh, God, I go back with Harrison, back in '77 at Columbus Circle, both us were wondering how long this was going to last. And Harrison is a very insulated, very intelligent, and funny – very funny, very witty, dry-humored – and when you tap into that, it's great. So when he got over there [to the Bulgaria set], and once we opened up – and he also worked on this character. He wanted to make it very personal. These are the kind of guys that you just don't say “Here are the lines. Do it or else.” “Really? No.” He worked on it. I didn't know if we were ever going to work together, but on this thing we became very, very close. And I was just actually talking to him about his leg the other day, and I said, “Better you than me!” He was great. Anyway, we were having a great old time, and Harrison is special, very unique, and he can bring a lot to a scene with minimal effort.

On how they hope to perpetuate their career second acts (Gibson is 58, Stallone is 68):

Stallone: I'm not ready to sit at home and play with my Pomeranians 12 hours a day. I'm just not ready, so I think you keep going. Remember in old vaudeville, there was a cane that snatched you off the stage? Well, I'm waiting for that. Until they just hook me and go, that's it. Actors don't want to retire. They're usually forced to retire, and that's a sad thing because you really get better as you get older. You may not remember as much dialogue, but what dialogue you do remember, you're better at it! We're just all children. We're there to perform, and when that's taken away – I've always said that the artist dies twice: the first death is the hardest, which is the career death, the creative death; the physical death is an inevitability. So I think everyone should just keep going, and I think that's happening. I think the genre's opening up, and television is providing more alternate career or second acts in an adult actor's career.

Gibson: Primarily, I think the most fun you can have standing up is directing a film, I think, and it's my primary talent – that's my gift, I think, as a director. So I'm going to pursue that. I've got a few irons in the fire. It doesn't pay to talk too much about it, because industrialist espionage is rife! Say anything, somebody swipes the idea. “That's a good idea – we should do that!” It ends up on TV or something. But that's OK, too: I'll direct TV. It's great – TV's getting amazing. So I definitely have my sights set on that and will do, yes.

And lastly, this little nugget about Stallone’s first encounter with the grandfather of all action heroes:

Stallone: I walked in a room and there was John Wayne. I'll never forget this. And I'm going to rent the tuxedo, this baby blue tux – I still have the picture of it – big, stupid bow tie, and it was for the People's Choice Awards. And I see this man, this big guy, coming towards me. And he walks over and he goes, “Hello, my name is John Wayne. And I want to welcome you to the business.” And I went, “Goddamn!” But that gives you an idea of the class of the guy.

The Expendables 3 opens today nationwide.