Floyd Mayweather, Jr. learned an important lesson last week while training for his comeback fight in Las Vegas. He learned he’s not a kid any more.

The 32-year-old five-time world champion was forced to postpone his scheduled return to the ring next month against Juan Manuel Marquez because of a rib injury that no one yet knows the severity of. Mayweather issued a statement saying he was disappointed about having to delay his return to boxing and Marquez issued a statement saying he was disappointed that Mayweather had disappointed him by delaying his return to boxing but would be ready whenever he is to square off at the contracted weight of 144 pounds.

What we don’t know are many things including the severity of the injury, the number of weeks Mayweather will be unable to train and, most of all, whether he really has a rib injury in the first place or whether he was just having a tough time getting some weight off from around his ribs as he fought to get back down to 144 pounds, the lowest weight he will have fought at since 2005.

Mayweather is a gym rat and almost always in condition so conditioning itself is not an issue. But at 32 he may be finding out what we all do, which is paring off the pounds is not as easy after 30 as it once was.

Then again, maybe it was simply a training injury as announced, which certainly someone trying to come back from what will now be at least 21 months of civilian life might have expected. Such setbacks when trying to remind your body of what it once was are not unusual. In fact, they are the norm. So the announcement that Mayweather had asked for a postponement was hardly earth shattering news. Butit was a reminder that comebacks for fighters over 30 are no easy task and nothing to take for granted.

It is now anticipated, although not etched in stone, that he and the soon-to-be 36 year old Marquez will face each other on Sept. 19, a Mexican Independence Day weekend which quite often features a big fight in Las Vegas with an Aztec warrior as the headliner.

Marquez (50-4-1, 37) would fit that description and the roughly $4 million he’s been guaranteed to face Mayweather seemed to insure he isn’t going any where but Las Vegas any time soon. For him the concern is deciding whether to stop and then re-start his training or stay in the hills of Mexico to continue preparing for a fight with the undefeated Mayweather without knowing quite when it will be.

This is not as easy a decision as it might seem. A break for at least several weeks would be logical to avoid going stale by over training but until a new date is set Marquez cannot know for sure if the fight will come in August, which seems unlikely, and thus would demand he keep working or October, which is possible and then would obviously result in abandoning his present camp for a brief respite before returning to hard training himself.

As for Mayweather, Golden Boy Promotions has already stated they do not believe Mayweather broke a rib, instead speculating that it is a cartilage problem which would mean bruised ribs and a layoff of several weeks while they heal.

If the fight can be rescheduled for Sept, 19 (and there will be many factors there including HBO’s schedule, the MGM’s already planned events for that very popular weekend in Las Vegas and Mayweather’s healing powers), it should be easy enough for both fighters to begin training anew.

But if it drags on for a protracted period, or if Mayweather suffers any further setbacks, problems could follow that will not be as easy to solve.

Although Marquez badly wants to face Mayweather, he also wants to be sure he has another big payday before the end of the year. If anything else were to happen to Mayweather that could delay their fight further it would put his plans in jeopardy and at his age it is not wise to linger too long away from the sport.

Mayweather faces different problems. If he fights in September he will be coming off a 21-month layoff since he destroyed Ricky Hatton in December, 2007. That is not a significant problem because of his vast skills and the fact he never really gets out of shape. The problem comes if he were to sustain some sort of second injury or re-injures his ribs and again has to step a way from training.

He would then be forced to either ask for another postponement that could lead to Marquez looking at other options (Manny Pacquiao III?) or fight at less than 100 per cent to insure he doesn’t lose a shot at Marquez, which may not be to his liking either after 21 months away from the ring.

All of this may prove to be a moot point if Mayweather simply comes back into training in a few weeks with sound body and mind. But the fact is these are the kinds of things that happen to 32-year-old fighters who leave the arena for a protracted period and then decide to come right back against top level competition.

Boxing is not like piano playing, although Mayweather quite often makes it look and sound like beautiful music when he’s at his best. It is not like riding a bike, either.

Certainly one can leave and return but two years away is a long time, especially when one is asking their body to fight at a weight (144) it has not had to get down to in over four years. The effort to do that can lead to injuries and concerns.

Maybe Floyd Mayweather, Jr. has neither. Perhaps this was a simple training injury that could happen to anyone at any age and at any time.

But when it happens to you in the midst of a comeback against one of boxing’s finest craftsmen it makes people think about a lot of downside possibilities. The fact is those exist not only for Mayweather but also for Marquez if the postponement turns out to be anything more than one of minimal duration. If that happens, who knows what will follow?

Regardless, what Floyd Mayweather, Jr. learned last week when his ribs began to ache is that starting over in boxing at 32 is not as easy as getting in it at 22.