Veteran boxing analyst Larry Merchant has been pushing hard for a super showdown between Floyd Mayweather Jr. and Manny Pacquiao for the past four years.

While several boxing experts have already ruled out the possibility, Merchant is still optimistic that the two boxing superstars will eventually settle their differences and face off inside the ring before ending their respective careers.

Merchant admitted that the potential record-breaking showdown will not happen anytime soon, but he quickly insisted that the super fight is bound to happen, citing boxing superstars who eventually agreed to collide during the twilight years of their careers.

"I've been telling people for three or four years that I thought it would happen and I've been consistently wrong, so I don't claim to be an expert on that because obviously there are other considerations for both of them," Merchant told BoxingScene. "They've made a lot of fights. They've made a lot of money. And it's not going to happen anytime real soon. But listen, Tyson and Lewis didn't happen in their primes and yet it was a huge event when it happened."

But for the highly-anticipated showdown to happen, Merchant stressed that Pacquiao has to prove that he still has a lot of gas left in his tank to earn a shot against the reigning pound-for-pound king.

"I think there's a question about Manny and whether he's the Manny of story and song, whether he's really going to be an elite fighter for very long," Merchant said.

Mayweather is still undefeated in 45 fights, and is coming off two straight convincing victories last year.

The 36-year-old Mayweather scored a lopsided unanimous decision win over Robert Guerrero in May last year, which was followed by a convincing victory against Saul "Canelo" Alvarez in their record-setting showdown in September.

Pacquiao, on the other hand, still has a tainted reputation, according to Merchant, because of his twin defeats to Timothy Bradley and Juan Manuel Marquez.

The former pound-for-pound king made a triumphant comeback in November when he scored a unanimous decision win over Brandon Rios, but Merchant insisted that Pacquiao did not perform well enough to prove that he is still on Mayweather's level.

"It showed that he's a very special athlete who was able to make yet another reinvention of himself. Whether he can beat an elite opponent using that style or if he has yet another gear we don't know," Merchant said.

Pacquiao will have a chance to impresse Merchant soon as he is set to face Bradley in a rematch on April 12 at the MGM Grand in Las Vegas.

See Related: Pacquiao To Face A Confident Timothy Bradley On April 12

Mayweather will also make his return to the ring on May 3 against a yet-to-be-named opponent, with recent reports suggesting that the flamboyant American will soon announce a fight against British boxing icon Amir Khan.