London Calls

There are two more days and three more matches left in the ATP's season. Here's a quick look ahead at Sunday's semifinals in London. They could be blockbusters, they could be busts, but they've got four great and deserving players in them.

Rafael Nadal vs. Roger Federer

Nadal has won 21 of their 31 career matches, seven of the last nine, and all three so far in 2013. But Federer still has one head-to-head advantage: He’s 4-0 against Rafa indoors, and all four of those wins came at this event, the World Tour Finals. This is Federer’s last stronghold against his younger rival.

Will the court and the roof and the presumably rowdy pro-Federer London crowd make a difference? It won’t hurt. Plus, the last time these two played, on outdoor hard courts in Cincy this summer, Federer did win a set. He has also looked better each week this fall, and he may have played his best, grittiest, even speediest set of tennis in 2013 to come back and beat a top-notch opponent in Juan Martin del Potro on Saturday. So there are reasons to think Federer can get on the board against Rafa this season.

There are also reasons to think he won’t, most prominently that last set of tennis against del Potro yesterday. Federer played well, obviously, but he played while Rafa rested. Nadal will come in after a day off, and he’ll come in having lost just one set in three matches this week. Rafa hasn’t been at his absolute best; he was inconsistent in beating David Ferrer, his forehand sat up against Stan Wawrinka, and he lost his first set to Tomas Berdych in their last six matches. But Nadal also made it clear that he’s here to win this tournament for the first time. He was happy, obviously, to clinch No. 1 for the season; but he was almost as happy to clinch the top spot in his group, so he could avoid facing Novak Djokovic in the semifinals. Rafa may not have played his best here, but he’s competed like a No. 1. For the first time since the U.S. Open, it's felt like he has a title to gain, rather than a ranking to hold onto.

Federer ran away with their last match in this arena, 6-3, 6-0, in 2011. But the bounce in the O2 isn't as low this time, and the court isn’t as fast; both of those factors should help Nadal. And while Federer put on a great show in the third set against del Potro, he hasn’t played great this week, either. Federer says he needs to think of himself as the underdog in this match, and a free-swinging attitude will likely help. Nadal, the master of playing the underdog in their rivalry, could get tight if he starts to believe that a loss to Federer would be a bad one. Roger will want to make it a hitting session and get it over quickly; Rafa will want to make it a running session, and not panic in the face of any early, crowd-backed Federer storm of good play. If necessary, Rafa will be happy to make it last awhile. It could come down to forehands: Is Federer’s shanking, or clicking? Is Nadal’s sitting up, or powering through?

The Pick: Nadal in two sets

Novak Djokovic vs. Stanislas Wawrinka

It’s fitting that we get a Nole-Stan showdown to close the season, because the two of them christened 2013 with their classic 12-10 fifth set at the Australian Open back in January. Djokovic won that match, and another five-setter over Stan at the U.S. Open. In fact, he’s won all 13 times he’s played Wawrinka since 2006.

Djokovic also happens to have won 20 matches, three tournaments, and two Masters events in a row, and he’s the defending champion in London. But he’s had a hiccup or two there this week. Three of them, in fact; he lost one set each to Federer, del Potro, and Richard Gasquet. He even lost control of his body for a game against Federer. But each time, once he’s worked though his nerves and frustrations, Djokovic has settled down and played clinical, airtight tennis in the third set. The slower court at the O2 has been been right up his alley.

Does Stan have a chance? One bright spot is that in both of their Grand Slam matches this year, he came out firing and won the first set easily. And I would expect him to put together a run of games at some point during this match. He'll have nothing to lose, at least at the start, and even Nole can't catch up to his backhand down the line when he's timing it well. But Djokovic will obviously know that, in two-of-three, he has less time to mess around than he does at the majors. He won’t finish the year No. 1, as he has the last two seasons, but a win at this event could send him back in that direction in 2014. For his part, Wawrinka may be happy to have gone this far in his World Tour Finals debut. Stan's come a long way this season, but Nole's still in front of him.

The Pick: Djokovic in two sets