It was the punch of the year, and perhaps a punch for the ages.
It was a sensational punch delivered with speed, power and perfect accuracy. To his part, Pacquiao helped with the punch's effectiveness because he was moving forward and into the sweet spot for Marquez.
At the time of the punch—the final seconds of the sixth round—Pacquiao was starting to get the best of it in the fight. He had overcome an early knockdown, had knocked down Marquez himself and he was peppering his rival with hard punches.
Just for a few seconds, Pacquiao seemed to stop respecting Marquez and his immense power. Marquez turned out the lights and the fight was over in the most decisive of manners.
If Pacquiao has any physical symptoms or tremors that would keep him from performing at his best in the ring, he should not be allowed back in the ring and allowed to continue to box.
It is just that simple. No fighter should be allowed to get in the ring if he is not able to reach a physical peak. If Pacquiao was permanently damaged by the knockout punch that Marquez delivered—or any other punch he has taken during his 18-year career—he should not get back in the ring.
But once he passes the medical exams, it may not be as difficult for Pacquiao to come back from the emotional trauma of getting knocked out.
Pacquiao has been a professional boxer since 1995. He was an amateur long before that. Every time he has gotten in the ring, he has understood that he could get knocked out at any time.
When Pacquiao is in the ring, he is trying to take out his opponent. That's just what his opposite number is trying to do as well. It is his job to protect himself at all times and if he doesn't, he has a chance to get knocked out.
That's what happened last December against Marquez and that's what happened twice before in Pacquiao's career. He was knocked out in 1996 by Rustico Torrecampo and he also suffered a technical knockout in 1999 at the hands of Medgoen Singsurat.
Pacquiao came back from those of one-sided defeats with long unbeaten streaks.
So as stunning as the knockout loss to Marquez was, it was not completely unfamiliar territory for Pacquiao.
Pacquiao is a professional boxer and he knows the risks. He also knows he has to move forward if he wants to get back in the ring.
As soon as he seriously starts training for his next fight, Pacquiao won't be looking back any more and he won't be worried about the loss to Marquez.
His fans may still have concerns, but he will be looking forward to getting back in the ring and dominating in his next fight.