IF Floyd Mayweather doesn’t come out of retirement to fight Conor McGregor, his greatest boxing foe Manny Pacquiao would be willing to take on the UFC megastar.

Hype continues to build around the possible Mayweather v McGregor bout, which would be arguably the biggest fight in the history of combat sports. Pacquiao has been an interested observer but, like most, isn’t quite sure what to make of it.

“I don’t know if they are taking it seriously. It’s on the news but I don’t know if it will happen,” Pacquiao told Fox Sports News 500 in an exclusive interview.

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Conor McGregor and Manny Pacquiao. Source: Getty Images

Pacquiao, however, is open to the possibility of fighting McGregor himself if the Mayweather bout falls through, saying he’d have no problem stepping in the ring with him — on one condition.

“In boxing? In boxing (I would) but not in (UFC), just boxing,” he said.

Asked whether he thought McGregor could last 12 rounds with him, Pacquiao said: “I’m sure he will be moving around.

“I didn’t see it [footage of Conor sparring]. But if we are talking about Conor McGregor and boxing, it’s different. Boxing is different than MMA.”

WBO welterweight world champion Manny Pacquiao. Source: AFP

The 38-year-old Filipino is set to take on Australian Jeff Horn in his next fight but wants to keep fighting beyond that, with a goal to fight “three or four times” in the next two years.

A rematch with Mayweather following their 2015 is high on the agenda but it’s very much a wait-and-see proposition.

So, does he give history-making mixed martial arts champion McGregor any chance against his great rival, if that fight ever goes ahead.

“I don’t think so.”