OK, here’s the million dollar question: What does Rafael Nadal do for an encore in 2014? Left for dead (athletically) with bad knees midway through 2012, he rebounded after an angst-filled, seven-month layoff to succeed beyond his wildest dreams in 2013. He won 10 titles (including two of the three Grand Slams he played), finished the year 75-7, and reclaimed the No. 1 ranking.

Now that he’s gotten over his second “career interrupted” interlude (his vulnerable knees also forced him to take a significant hiatus in 2009), Nadal has some interesting decisions to make, starting with the granddaddy of them all: Should he invest his heart and soul in an effort to surpass Roger Federer’s record of 17 major titles?

Nadal has a great shot at the honor. At 27, he’s at the peak of his physical powers but also experienced. He already has 13 majors, and it’s easy to imagine him winning three to five more French Open titles alone.

Ad-In: With healthy knees, Nadal is a lock to bag his ninth title at Roland Garros. And with wins over his main rival Novak Djokovic in two Grand Slam tournaments in 2013 (the French and U.S. Opens), Nadal has sent a strong message—and earned a strong psychological advantage going into the new year. Given that he’s not a man to waste opportunities, it will be up to his rivals to step it up and block his ambitions.

Ad-Out: Knock on wood, but the reality is that Nadal's own knees may be his most formidable rival. But they certainly aren’t the only ones. While Nadal ripped the No. 1 ranking out of Djokovic’s hands in 2013, Djokovic once again demonstrated at the end of the year that his A-game remains more than Nadal can reliably handle.

As we approach the new year, we'll take a closer look at what's in store for the past year's top performers. To read more of our 2014 Season Previews, click here.