Manny Pacquiao has been a dominate force as he was against Shane Mosley, but the biggest fight of his career may take place against Floyd Mayweather. Reuters

Heavily favored Floyd Mayweather Jr. takes on Victor Ortiz with the WBC welterweight title on the line on Saturday, September 17th, at the MGM Grand in Las Vegas, Nev.

For many boxing fans, this fight serves more as a tune up for Mayweather as he gears up for an eventual mega-bout with Manny Pacquiao, in what would be billed as the most anticipated fight since Mayweather fought Oscar De La Hoya in 2007.

The big questions is, will it happen?

First Mayweather will have to defeat Ortiz, and then Pacquiao will have to defeat Juan Manuel Marquez, when they fight for the third time in November.

Both are likely to happen, but it won't be a sure thing. However, there's a good possibility a Mayweather-Pacquiao bout could take place even if one of the two fights doesn't go their way, or if their respected fights ends controversially, which has been known to happen.

According to Jeff Mayweather, Floyd's uncle, the fight will happen, but not until 2013.

I think he [Mayweather] will be fighting another couple of years, Jeff Mayweather said to I think that's being realistic because I think the fight that's out there will take that long to materialize.

There has been constant back-and-forth between the Floyd Mayweather and Manny Pacquiao camps. Most of the problems stem from Mayweather demanding that Pacquiao adhere to thorough drug testing, which Pacquiao has accepted. However, there is still some debate about which agency does the testing, as Mayweather uses the United States Anti-Doping Agency to handle testing for his fights and requires random testing.

Pacquiao has retaliated with a defamation suit against Mayweather for the accusation that the Filipino star used performance-enhancing drugs.

Last month, Bob Arum, CEO of Top Rank, posted this message on Twitter: There are no issues holding up a Pacquiao- Mayweather bout.

ESPN's Dan Rafael recently spoke with Arum, and the long-time promoter said, Manny has taken the position that he would agree to unlimited testing, Arum said. It is a non-f------ issue.

While Jeff Mayweather expects that the two high-profile boxers will battle in the next two years, Arum doesn't see it happening.

I'm not optimistic, Arum said. I think Mayweather will look for a way not to do the fight. I smell the initial drum beat of 'You're not allowed to train in the Philippines' because of [who oversees] the testing. Once Mayweather says that, he can go f--- himself. Then it becomes a major political issue when he says Manny can't train in his home country. Besides, nobody would subject themselves to that type of restriction.

In the mean time, both fighters might move on to other opponents. Mayweather has been mentioned in a possible bout with British star Amir Khan, while Pacquiao may be challenged by Tim Bradley, an elite boxer who many consider to be in his prime.

Should both Mayweather and Pacquiao look elsewhere for their following bouts, Jeff Mayweather may be right about 2013, though Floyd probably wouldn't have wasted his time with Ortiz's southpaw stance if he didn't have at least had some interest in Pacquiao. There really is no reason for Pacquiao to need another fighter before he faces Mayweather considering he's fought many of Mayweather's opponents.

Pacquiao may go into politics full time, and Daily Mail recently reported that Mayweather has until the end of 2012 to agree to a fight.

The elephant in the room is money. Mayweather and Pacquiao may be nearing retirement, as both are well into their 30s, and a Pacquiao-Mayweather championship fight could pay both boxers an estimated $50 million a piece.

A major question is whether this long build up leading up to the potential fight will generate more interest, or whether all of the back and forth is causing people to be actually lose interest.

Time, a precious commodity in boxing, will tell.