By Miguel Rivera

Top Rank's CEO Bob Arum has no idea if a rematch between Manny Pacquiao and Floyd Mayweather Jr. will actually take place - but he gives the fight a very good possibility of happening in the first half of next year.

The first fight, in May of 2015, generated $600 million in revenue and brought in 4.6 million pay-per-view purchases.

A rematch would not come close to doing the same amount of business, but even 50% of the previous numbers would make it by far the most lucrative matchup to make. Since their mega-match, no fighter has been able to break a million purchases on pay-per-view.

For the first time, Mayweather (49-0, 26KOs) showed up at a Pacquiao fight and sat ringside to watch him capture the WBO welterweight title from Jessie Vargas from the Thomas & Mack Center in Las Vegas. Pacquiao (59-6-2, 38 KOs) would like to fight again in May.

Mayweather has been retired since last September, but he appearance at Pacquiao's fight has created a lot of speculation that he's interested in coming back for a 50th fight next year - against Pacquiao.

During the first time around, there was a lot of bad blood between the two camps and it took them over five years to reach an agreement.

According to Arum, the two sides are now on good terms and a new agreement would be much easier to make the second time around. After years of hostile feelings, Arum is even on friendly terms with Mayweather's adviser, Al Haymon.  

"Floyd came to the fight," Arum told ESPN Deportes. "Now, that doesn't mean that the fight will happen, but if it does, it won't take a long time to make because the animosity that was there before the first fight is gone. There's no more animosity between the camps."

"It doesn't mean the rematch will happen, though, but it means the tension is gone. The bad words are not there. If the fight does happen it will be easier to make."

"It was so tense last time, but it won't be that way now because everyone can get along. Like everyone else, I'm guessing there will be a rematch. He did come to the fight. I give it 75 percent. Do I know it's gonna happen? No. Do I know if Floyd wants the fight? No. I know nothing more than the public knows at this point and what I observed."