LONDON - World number one Novak Djokovic pulled out a near-perfect performance as he downed the resurgent Rafael Nadal 6-3, 6-3 in their World Tour Finals last-four clash on Saturday. Djokovic was beaten by Roger Federer in the group stages of the season-ending tournament, disputed on a hard court between the year's top eight players at London's O2 Arena.

Spanish fifth seed Nadal won all three of his group matches to reach the semi-finals but there was little he could do to stop the defending champion in this sort of form. Djokovic will play either Federer or his Swiss compatriot Stan Wawrinka, the French Open champion, in Sunday's final.

If the Serb lifts the trophy for a fifth time, he will become the first player to win the Tour Finals four years in a row. Djokovic, the Australian, Wimbledon and US Open champion, hit 24 winners to nine from Nadal, who could not fashion a break point throughout the match.

"It was a great performance, no doubt about that, from the very beginning. I managed to execute the game plan, I was trying to be aggressive, dictate the play," Djokovic said. "He was playing some great tennis during this week but I managed to pull out my best game when it was needed the most."

While Federer and Nadal's epic clashes down the years have led their rivalry to be regarded as the sport's must-see match-up, the Spaniard's duels with Djokovic have grown increasingly ferocious since their first meeting way back in 2006.

Nadal held a 23-22 edge in his head-to-head record with Djokovic going into the match, but the Serb had won seven of the last eight meetings, including the quarter-final victory that ended the Spaniard's long reign as French Open champion earlier this year.

After a miserable 2015 campaign, Nadal had looked somewhere close to his best over the last week as he moved into the semi-finals with three successive wins. But the world number five had not done his chances of defeating Djokovic any favours by engaging in a bruising marathon victory over David Ferrer in a meaningless group match just 24 hours earlier.

While Nadal was pushing his body to the limits, Djokovic was at home relaxing having finished his group campaign on Thursday and unsurprisingly there was noticeably more zip to the Serb's groundstrokes in the first set.

In front of 17,800-strong capacity crowd, including football icon David Beckham, Djokovic quickly took control as he unloaded a string of searing winners to break in the second game. It was an emphatic statement of intent and Djokovic backed up his early dominance with a flawless display that gave him the first set with ease.

Nadal was staying in the contest, but on the big points, Djokovic was able to bring something extra to the contest. In the second set, Djokovic broke again for a 3-2 lead, stretching out for and salvaging lost causes and beating his opponent with pace and clever angles. Serving to stay in the match, Nadal was forced to deuce as Djokovic had the Mallorcan scampering back and forth with drop shots and lobs. On match point, one last cross-court back-hand from Djokovic left Nadal flat-footed on the baseline, sealing the match in an hour and 19 minutes.