Boxing great Manny Pacquiao steps in to the ring tonight to take on a tough challenge from Timothy Bradley. All week, the lead up to the fight has been significantly focused on Pacquiao's current position in the boxing ranks. There's no doubt he is one of the true greats of this generation, but the closer we get to tonight, the more you begin to sense a common question in the air. That question:

Is tonight the end of the line for Manny Pacquiao?

A growing number of analysts are voicing their concerns about the future of the pound-for-pound great, saying that his mental game is off, and that he's not ready for this fight. Those who believe Pacquiao is not fully prepared for Bradley added more to their argument at yesterday's weigh-in. For the 147 pound Welterweight fight, Bradley came in at 146, Pacquiao at 147. That's notable for Pacquiao as, although it's right on line for the division, it's also the highest he has ever weighed in. And this is not 147 pounds of muscle, as instead he looks a bit out of shape. With a lot of questions about Manny's focus heading into this fight, a small detail like this can become very telling.

Is Manny Pacquiao not mentally prepared for Timothy Bradley, and did we see a clear sign of that at the weigh-in? And if so, does that mean the legend is primed for a fall? It's certainly a theory that many people hold, including Bradley:

"He's worn out, tired, I can see it in his eyes, the wrinkles," said Bradley, a 5-1 underdog despite his unbeaten record of 28-0 with 12 knockouts. "This boy's not ready for me."

More after the jump.

More Pacquiao-Bradley Coverage From SBN
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And here's HBO analyst Emanuel Steward on how Pacquiao looks heading into the fight:

"I see a slow slippage in his delivery," Steward said. "The animal-like intensity is slightly less than it was. That's the legs. That's what I always look at. It might not be there to the untrained eye, but you'll see . . . a guy like Bradley - a good, young, intelligent fighter - can exploit those weaknesses. This is not a good fight for Manny."

Finally, here's Jim Lampley on why, if Pacquiao is not ready, Bradley is the perfect opponent to take advantage of that weakness:

"(Bradley is) the most frequent (head) butter in the sport. To say that he's probably guilty of more accidental head butts over the course of the last 10 years than even Bernard Hopkins is saying a lot. A lot like Evander Holyfield, he leads with his head and it's a big head, and it gets in the way of people. The bottom line is Manny Pacquiao doesn't like blood."

Perhaps people are making too much of the weigh-in. Perhaps people are reading too much into Manny struggling against Marquez last time out. Perhaps. But this much is definitely true - for the first time in a number of years, there's a real sense that Manny Pacquiao could be defeated tonight. In his time at the top, Pacquiao has helped push a number of fighters into retirement. Tonight, Bradley will look to turn the tables and forever dethrone the legend. And as the fight draws near, it seems more and more likely that he just might do it.