One to Go...

Two sets of round robin matches are in the books at the year-end championships, and now we're starting to get a clearer picture of who will ultimately be playing for the title -- and a couple men you might not have expected are really taking the chance to shine. But with everyone still having one match left, there's still a lot that can happen, and even for those who've already clinched a spot in the semis, there's still a lot on the line.

Group A

Novak Djokovic, undefeated since August, was the clear favorite among the first group of London qualifiers, but he's not the one who's been most impressive so far. Roger Federer, who's had a couple early losses since the U.S. Open had fallen to the third seed this week but came out firing anyway -- after an easy win over Tomas Berdych he absolutely pummeled Nole on Tuesday, making himself the only undefeated player among these four and securing his ticket to the semis. Nole isn't totally out of contention, of course -- he opened with a quick win over a struggling Kei Nishikori on Sunday. But the man from Japan, who only just made the cut for the World Tour Finals having lost in the first round in New York and retiring at the Paris Masters, bounced back from his early loss by notching his own win over Berdych. How these two guys perform tomorrow will mean everything -- Kei's beaten Roger more than once before and another victory could earn him a spot in the final four or push the Swiss into second place for the group. And Djokovic, still hoping to reach the semis, could even vault back into the first spot, giving him a big advantage when things really become heated.

Group B

Of course the bigger surprises came in the second group of finalists. Rafael Nadal, who despite his many honors has never won in London, has been famously up and down all year long. But he opened by avenging his Paris loss to Stan Wawrinka and then stunned Andy Murray in his second match today, scoring his biggest win since last year's French Open final. Like Roger he's now the only one in this bunch who hasn't lost this week and he's also booked his ticket to the semisfinals. He has a good shot at keeping his top spot too -- he has a solid 23-6 record against David Ferrer, his only remaining opponent -- but the veteran Spaniard did beat him last year in Monte Carlo and has arguably been the more consistent player over the last few months. But the bigger battle will certainly be between Murray and Wawrinka, a pair of powerhouses who've nearly split their head-to-head -- neither have reached the final in London yet, but both have come pretty close. And while it seems like they're just playing for second place in this group, the opportunity could still be great -- they're both gaining ground on both Roger and Nole, so whoever ends at the top of the other section will be in for a fight as soon as they get back on court

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So perhaps things have gotten a bit more interesting than we were anticipating at this year's ATP Championships, but it certainly seems like we're seeing a couple players really upping their games at the end of the season. And while the competition will only get more intense from here, the ones who've shined brightest might just be the ones best able to take advantage.