Manny Pacquiao called out Floyd Mayweather Jr. once again on Twitter, urging the reigning pound-for-pound king to face him in a potential record-breaking showdown this year.

Before 2014 ended, Pacquiao, who has made it no secret he badly wants to face Mayweather in May, said on Twitter they should not let this year end without giving boxing fans the fight they have been asking for over the past several years.

"The ball will drop at midnight to usher in 2015. @FloydMayweather let's not drop the ball on fighting each other next year! #LetsMakeFistory," Pacquiao posted on his official Twitter account.

Mayweather recently gave the strongest indication so far that he is willing to face Pacquiao after previous negotiation for the historic fight went down. The unbeaten junior middleweight and welterweight champion said Pacquiao should agree to face him on Cinco de Mayo weekend on May 2 -- a challenge accepted by his Filipino rival.

The two sides are still negotiating for the fight with reports indicating that no deal is imminent at this point.

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Michael Koncz, Pacquiao's legal adviser, told Lem Satterfield of Ring TV they recently received a new offer from Mayweather's camp through Top Rank Promotions, who has a promotional deal with Pacquiao.

"We're still in negotiations with Floyd's group through Top Rank," Koncz said. "I spoke to Manny this morning. I gave Manny what is perceived to be a counter offer from the Mayweather people."

Koncz did not specify the new fight terms included on Mayweather's counter offer, but he said there have been numerous exchanges of counter offers over the past several weeks.

"We discussed it and now I've given instruction to Bob to counter their counter. We've been going back and forth," Koncz said. "Bob has been negotiating with the powers that be on Floyd's side for the past couple of weeks. There's been offers and counter offers, and a couple of days ago Bob called me and gave me allegedly where Floyd's side is, and I discussed that with Manny.

Koncz added that the recent exchange of counter offers shows that both camps are really willing to discuss the fight, but he said there is no reason to be optimistic until Mayweather signs an official contract to face his biggest rival.

Revenue split is reportedly the biggest hurdle in the negotiation, but Pacquiao recently said Mayweather could get the amount he wants just to make the super showdown happen this year.

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