My 2013 Sportsman nominee: Tennis player Rafael Nadal

Sports Illustrated announced its choice for 2013's Sportsman of the Year on Dec. 16, 2013. Here's one of the nominations for that honor by an SI writer.

I never envisioned naming Rafael Nadal as my Sportsman of the Year, but I'm like most of Nadal's opponents. He wore me down.

There have been better tennis years than Nadal's 2013. But I can't remember one that impressed me more. In January, Nadal was finishing a seven-month layoff because of a left knee that seemed to shred a little bit with each match. He missed the Australian Open. There were legitimate questions about when he would play again, and more importantly, about how he would play again.

He finishes the year at No. 1 in the world. He won the French Open, because he always wins the French Open, and he won it with another epic performance in a career full of them: 6-4, 3-6, 6-1, 6-7 (3), 9-7 over Novak Djokovic. Sure, it was the semifinal, but the final was just paperwork.

Nadal lost in the first round at Wimbledon, but that just made his French Open title seem more amazing; he was still not really back, but he won the French anyway.

Then, in September, Nadal dispatched Djokovic again, this time for the U.S. Open title, and it was the strangest sight. Djokovic dominated the points, but Nadal somehow dominated the match. Nadal had one ace. He had 27 winners; Djokovic had 46. He won because he just would not go away, under any circumstances. He stayed alive in points for as long as he could, any way he could, until Djokovic messed up.

Officially, Djokovic's errors were "unforced". We should know by now that against Nadal, all errors are forced. He forces them by refusing to make errors himself.

I don't know if Nadal is the best player ever. But in 2013, he convinced me: for one match, with my vital organs on the line, I would take him.

Again, I didn't think I would ever say that. For the longest time, I was a Roger Federer guy. I believed Federer was the best tennis player in history. His game was breathtakingly complete. He has won 17 Grand Slam events, but that is not even the most impressive Federer stat.

Federer advanced to the semifinals of 23 consecutive Slam events -- six straight years of consistent excellence, an astounding streak. It brings to mind one amazing thing about Federer's old friend Tiger Woods. At Woods' peak, regardless of the course set-up, he was the favorite. Links, tight tree-lined fairways, impossibly sloped greens, birdie-fest ... it never seemed to matter. If Tiger played well, he would probably win.

The only knocks on Federer were that Nadal often beat him, and that he was not dominant on clay. But I thought those were largely the same knock -- many of Nadal's victories against Federer have come on clay, where Nadal is the best ever, and anyway, Federer was still great on his weakest surface. Pete Sampras was a famous non-factor at most of the French Opens he played. For many years, Federer was the second-best clay-court player in the world, and when Robin Soderling stunned Nadal in the 2009 French, Federer won the tournament.

It has been written many times that Nadal's lefthanded power and high topspin neutralizes Federer's devastating backhand, and that has been Nadal's advantage when they play. Perhaps. But in 2013, we saw a more important difference.

Federer is so gifted that he never had to be as mentally tough as Nadal. Against 95 percent of Federer's opponents, the gifts were enough. Federer did not learn to win on guts and resourcefulness. This year, when his age showed, Federer did not have a strong enough mental foundation to save him. He just never had to build it. It almost isn't his fault. He was too good.

Nadal is a gloriously talented grinder; he fights his opponent with every shot. He is not as complete as Federer or Djokovic, and he isn't particularly graceful, but he is mentally sharper than either man.

For years, people wondered if Nadal's grinding style would force him and his knees into early retirement. We now see that it saved him from retirement. When he had to come back from that knee injury, he was ready. When he had to adapt, he knew how.

It is fascinating to wonder what would have happened to Nadal and Federer if Nadal had been the older man. Would an 18-year-old Federer, chasing a 23-year-old Nadal, have learned to grind out points instead of winning on skill? Would he have developed an underdog's brain?

We will never know. But I'm reminded of what somebody told me once, for a different story, about two other athletes. He compared them to Superman and Batman. Superman has the best superpowers and Batman doesn't have any, but "Batman thinks he can whip Superman's ass." That belief counts for a lot in sports. That's why my Sportsman of the Year is tennis' dark knight, Rafael Nadal, who started the year with an uncertain future, and ended it with a firm grip on his sport.