World No. 6 Jo-Wilfried Tsonga tells the Daily Telegraph that he's not positive if he can crack the game's upper echelon.
"I don’t know, but maybe somewhere in my head I think about it," he said. "In my head I am sure I can do that, and I try to do that. I know I am not as consistent. But maybe, one time, one will not play so good. And even if I am not as consistent, if I win a Grand Slam, and play well, I can be in the top four....The top four guys are so good. They all improve. It’s not about staying at your level, that won’t be enough to stay at the same ranking. To stay at the same ranking you have to improve because the other guys improved."