A rematch of the U.S. Open semi-final is scheduled to take place in the knockout stage of the Barclays ATP World Tour Finals on Saturday in London, as Novak Djokovic and Kei Nishikori cross paths once again to determine who will reach the final berth of the season at the year-end championships. Djokovic leads the overall head-to-head series 3-2 after winning their most recent match in Paris.

Following up on his remarkably breezy matches in London so far this week, top seed Novak Djokovic cruised past Tomas Berdych to remain undefeated in the round robin stage of the tournament and officially cement his year-end spot atop the rankings. While the score line was not as bizarre as his recent 6-2, 6-0 win over Berdych at the China Open, Djokovic only surrendered four games throughout the entire match to win 6-2, 6-2.

Djokovic has now guaranteed the year-end No. 1 ranking for the third time in four years – just the seventh person to achieve that feat in the history of the men’s tour.

Although Nishikori was expected to meet Raonic in the third and final round robin match on Thursday, WTF alternate David Ferrer instead greeted him in a match that would mark the only three-set contest of the entire event this year. While Ferrer would start the match in fantastic fashion and would win the opening set with relative ease, Nishikori stormed back to win the second two sets in decisive fashion to close out the match 4-6, 6-3, 6-1.

Nishikori’s three-set victory over Ferrer was his fourth straight against the Spaniard and sets him up for a spot in the semi-final round of the tournament. After Andy Murray lost the first set to Federer, Nishikori officially qualified for knockout stage of the tournament on his first attempt.

“It’s never easy playing against David because he’s very consistent from the baseline,” said Nishikori. “If I want to win, I have to do something to break his tennis. From the second set, I was more aggressive. The final set was almost perfect.”

While Nishikori surprised many by defeating Novak Djokovic in four sets to reach his fist Grand Slam final, he was unable to follow up on that victory, as he lost to Djokovic in straight sets when they met several weeks back in the semi-final round of the Paris Bercy. Sadly, this will likely be another straight sets encounter, as Djokovic has been near unstoppable on the indoor surface this season.

Prediction: Novak Djokovic in Straight Sets