Last year, Jo-Wilfried Tsonga narrowly lost out to his fellow countryman Richard Gasquet in the battle to claim the final spot for the eight-man World Tour Finals. Somehow, it wasn’t surprising. While Tsonga has atomic strokes, his killer instinct has always been in question. What’s the opposite of a “closer?”

Tsonga promised much when he made the finals of the Australian Open in 2008, and he’s come within a hair’s breadth of duplicating that feat—and more. He’s been a Wimbledon semifinalist twice and he had match points against Novak Djokovic in the 2012 French Open. Unlike Gasquet, he’s also bagged a Masters 1000 title. Injuries have been a consistent theme in his career, but an even bigger one has been his tendency in big matches to enjoy the moment more than to seize it. Thus, he lets opportunity slip away.

Tsonga parted with coach Roger Rasheed in August; if he can further develop fitness and fighting qualities, the charismatic 28-year-old may yet win a Grand Slam title.

Ad-In: If Tsonga can remain injury free and develop greater mental toughness and physical fitness, it could turn him into a monster. He can rain down aces with the best of them, yet he has soft hands and can do surgical work up at the net. His two-handed backhand is rock solid, and his forehand is volatile. With his offensive prowess, he’s capable of shutting down anyone.

Ad-Out: Tsonga is in a pretty good place—he’s in the Top 10, making oodles of money, and wildly popular because he seems so laid back and, well, friendly. But charisma won’t win you Grand Slam trophies, and if Tsonga isn’t careful he just may end up being known more for his ability to entertain than to rise to the challenge of digging deep and answering the challenge of greatness.

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.