It's never easy being number one.

Following his rather routine retiring of Marco Antonio Barrera, 130-pound king Manny Pacquiao is being called out by everyone, their mother, and their mother's goldfish.

Pacquiao, who had trouble making weight to fight Barrera (and it showed in many ways), stated in an interview that he would like to take his next fight at 135 pounds. To me, this seems like a big leap for a guy who came into the sport as a strawweight. Power doesn't always move up a weight class with you, and while Manny is a very strong puncher with great hand speed, it takes a special fighter to move up that much over a career. Mayweather took one fight at 154 pounds and it wasn't really there, as he had to rely on natural athletic ability and great technical skill to beat Oscar de la Hoya.

Even just recently, we've seen plenty of big-name fighters go up too high. Oscar had no business as a middleweight, and Bernard Hopkins proved it. Winky Wright is not a 170-pound fighter. Shane Mosley struggled over welterweight. Ricky Hatton's lone fight at 147 was a near-debacle for his career. Arturo Gatti and Diego Corrales were not welterweights.

The rumor is that Pacquiao desires a fight with 135-pound champion David Diaz, who retired Erik Morales in August. Diaz is not a big puncher, but he's a sturdy, rugged fighter who will trade blows and not back down. Naturally bigger than Pacquiao, that could make a real difference.

But Diaz isn't the only name being floated, and in fact, he's probably the smallest name.

Knockout sensation Edwin Valero wants Pacquiao. Joel Casamayor wants Pacquiao. Joan Guzman wants Pacquiao. Michael Katsidis wants Pacquiao.

Valero, after the Pacquiao-Barrera fight, said of Pacquiao, "All speed and no power." A fight between the two would likely take place in China, as Valero is unlikely to receive medical clearance to fight in the States. Pacquiao once said he has no fear of Valero, who is 22-0 with 22 knockouts, because most of his opponents were "tricycle drivers."

Said Casamayor of Pacquiao's performance on Saturday, "It was mediocre at best. He's a regular fighter and he just comes forward and throws a lot of punches. Between me and you I think he's a maricon. He's calling out the lightweights like David Diaz and saying he wants to move up in weight, but he doesn't mention my name. I went up to his face a few days before his fight with Barrera and all he did was look at me and smile like a little girl. To me he's a B-level fighter at best."

Casamayor knows that any potential fight with Pacquiao would be a big payday for him. Valero knows the same thing. So do the rest.

Honestly, of these possibilities, there are two fights, on paper, that I'd love to see, but in reality would kind of scare the hell out of me. Pacquiao-Valero would no doubt be dynamite. But Valero's medical history is frightening every time he steps into the ring, and despite his interview-worthy comments, Pacquiao hits pretty damn hard.

The other one is Pacquiao-Katsidis. If you have yet to see Michael Katsidis fight, it's a sight. No one ever likes to talk about these things after the fact, but we can't ignore that he sent Czar Amonsot into an early retirement after their bout this summer. He hits like a truck. And at 135, Pacquiao's power, again, might not be what it is at 130. But there's no doubt the two would stand center ring and go to war. It's the type of matchup where you bite your nails worrying that the worst could happen to somebody. Pacquiao has improved dramatically over the years in terms of his defense, but you still don't have to twist his arm to get him to throw bombs and damn the consequences.

Pacquiao-Guzman is just an interesting matchup, although Guzman should concern himself more with Humberto Soto for the time being. I think of all the 130-pound fighters, Guzman presents the most difficult stylistic matchup for Pacquiao, from where I sit.

As for Pacquiao-Diaz, I'd be on board. But Diaz is probably going to have to survive Katsidis first.

All that said, and I know the weight issue might take precedence, and I, too, would rather not see it if Pacquiao isn't going to be 100% for it, Pacquiao-Marquez II is as close to a must-sign as there is. Their first fight was tremendous drama, and no one -- no one -- has outboxed Pacquiao like Marquez wound up doing that night. And who survives three Pacman knockdowns in one round, anyway?

My personal top five choices for Pacquiao's next opponent, including 135-pounders since that looks like a very real possibility:

1. Juan Manuel Marquez -- The rematch is natural. The first fight solved nothing, and both have gotten better since then.

2. Juan or Julio Diaz -- If Pacman does move up to 135, the winner of Saturday's Diaz-Diaz unification bout would be a great choice of opponent, and Manny's done so much that he doesn't need to prove himself worthy in a new class, at least not to me. Juan comes forward and bulls at his opponents -- it'd be interesting to see if he could back Pacquiao up. Julio is the less interesting case, unless, of course, he beats Juan.

3. Humberto Soto -- Two firecracker fighters. Nothing more to it than that. I just really like both guys. I was psyched for their fight that got scrapped in favor of Pacquiao-Barrera. After seeing Pacquiao-Barrera, who would've now preferred Pacquiao-Soto?

4. Joan Guzman -- Again, I think he presents a serious challenge for Manny, and I like when top fighters take risks. Even if they lose, at least they went for something tough.

5. Michael Katsidis -- What can I say? It'd be all-out warfare.

Honorable Mention: Zahir Raheem. Just to see how frequently Raheem would attempt to congratulate Manny with a mid-round hug.

As a bit of a side note, every fight now, they make a big deal leading up to it how "distracted" Pacquiao is. I always thought it was overdone until Saturday night. Pacquiao clearly controlled the majority of the fight, but he did have trouble with making weight. He did look gaunt at the weigh-in. He didn't look nearly as strong as he usually does, or even as fast. Manny was lucky he was in there with a retiring, half-motivated Barrera instead of a hungry Soto looking to make his name stick. Soto could've been real trouble for Pacquiao that night.

But whatever happens next with Manny, I'm sure he's going to take someone tough. With Top Rank and Golden Boy holding hands now, and the fall schedule being what it is because that's what fans have come to demand and expect, there's no more room for a Pacquiao time-filler like worn-out Oscar Larios or Jorge Solis.

Being the man comes with its price. Manny's going to have a lot of top fighters ready to sign on the dotted line. The game is truly on now, and we'll see if he's as determined to stay at the top of the heap as he was to get there.