The semifinals are set at the ATP World Tour Finals. The winner of Group A, Rafael Nadal, will be taking on the Group B runner-up, Roger Federer, in what will be their 32nd collision on tour. The second semifinal on Sunday pits the winner of Group B, Novak Djokovic, against the Group A runner-up, Stanislas Wawrinka.

Roger Federer (2-1) vs. Rafael Nadal (3-0)

While their rivalry has been dominated by the Spaniard, Federer comes into Sunday’s meeting with a 4-0 record against Nadal on indoor hard courts. The last time Federer and Nadal met on an indoor hard court came in the round-robin stage of the 2011 World Tour Finals, which Federer won in commanding fashion, 6-3 6-0. But Nadal has won seven out of the last 10 matches in their overall head-to-head.  Federer’s last victory came in the semifinals of Indian Wells in 2012.

Federer clinched his spot in the semifinals after taking out Juan Martin Del Potro in three sets for the second time in as many weeks. The Swiss trailed by a break in all three sets, including a 3-0 deficit in the third set that he managed to overcome before winning 7-5. The brand of tennis that Federer displayed against Del Potro was reminiscent of the Federer of old.

Nadal clinched Group A more easily after fighting off the resistance of Tomas Berdych on Friday. After being blitzed in the second set 6-1, Nadal steadied the storm and was able to reach the finish line 6-3 in the third set. Nadal’s victory capped of a perfect 3-0 round-robin record.

Despite the fact that Nadal has owned Federer throughout their careers, Federer’s 4-0 record against Nadal indoors is not overly astonishing. The quick conditions and lower bounces play right into Federer’s hands. Unfortunately, Federer will have to deal with higher than usual bounces on this particular court this year.

Nadal will surely maintain his usual tactics in this rivalry and look to exploit the Federer backhand as much as possible.  Federer’s serving will be crucial. He needs to win as many free points as possible off the serve and avoid getting into extended baseline rallies.

The two keys to this match as will be Federer’s break-point conversion rate and whether or not he can win the first set. Federer’s break-point conversion rate against Nadal is abysmal, and he has come back only twice after losing the opening set to Nadal.

While many would understandably claim that the Federer-Nadal matches are overhyped, it is still true that they offer us yet another chance to witness arguably the two greatest tennis players ever in action. And these opportunities may be limited. Each time that these two face each other may be the last time. And while Nadal has controlled this rivalry, spectators should approach each match knowing that they may have the chance to see these two legends at their peak.

Prediction: Nadal in three sets

Stanislas Wawrinka (2-1) vs. Novak Djokovic (3-0)

Wawrinka and Djokovic contested two of the season’s best matches in the fourth round of the Australian Open and the semifinals of the US Open, both of which Djokovic won in five sets.

Djokovic leads the head to head 14-2 and has not lost to Wawrinka since 2006. He has won four of their five meetings on indoor hard courts, breezing through in Paris last week 6-1 6-4.

Djokovic won all three of his round-robin matches in three sets to grab the top spot in Group B. Wawrinka won two of his three round-robin matches, beating Berdych and Ferrer in three sets en route to the semifinals. Wawrinka also got some help yesterday from Nadal, who defeated Berdych to confirm Wawrinka’s berth in the semifinals.

As with Djokovic’s match with Gasquet, the backhand-to-backhand exchanges in this match should be quite delicious considering the Swiss star’s blistering one-hander. But the key for Wawrinka in this match will be to serve big and end points quickly. In Paris, Wawrinka and Djokovic engaged in lots of grueling rallies, most of which were protracted and most of which were won by Djokovic. If he hopes to make inroads tomorrow, shortening the points and getting the first strike in will be vital.

Djokovic can beat Wawrinka on the offensive and the defensive. Wawrinka’s only viable strategy involves going right at the jugular. Under the tutelage of Magnus Norman, Wawrinka has developed a killer instinct in 2013. He will need this killer instinct to take down a man who has not lost since the US Open.

The belief will be there. Wawrinka knows that he can stick with Djokovic over a long period of time. Whether or not he can win the biggest points and shine in the biggest moments against Novak remains to be seen. Either way, the atmosphere and the intensity in the 02 Arena will be sky-high when they meet.

Prediction: Djokovic in three sets