It was a bad day for Switzerland, with Nadal a convincing 7-5, 6-3 winner over six-time champion Roger Federer at London’s O2 Arena.
Djokovic and Nadal have met 38 times before, more than any other two men in the Open era, with the Spaniard leading 22-16.
Nadal also leads 3-2 in their five matches this season, including both grand slam contests, but this tournament is the one major title he has yet to win. The 27-year-old said: “The most important thing is on the toughest surface for me to play, I was able to win four matches against top-eight players. That’s great news for me. It’s a very good way to finish the year.
“Now remains the last match. I hope to be ready for that. I know it’s going to be a difficult one. But I will try my best. I need to play my best match to have a chance tomorrow.”
Nadal has beaten Federer 22 times in 32 meetings and, with his first win over the Swiss indoors, his domination of the once great rivalry is now complete.
Federer still had his moments, especially a forehand winner at the end of an epic rally that enabled him to break back for 5-5 in the opening set.
But the poor service game he played straight afterwards was more indicative of a season that has brought him just one title and seen him slip to seventh in the rankings.
There must be a question mark about whether the O2 Arena has seen the last of the player it reveres more than any other.
Hearing Federer talk about the doubts that have crept in has been a fascinating insight into the mind of a great sportsman at the moment when certainty disappears.
But a final appearance in his hometown of Basel and semi-finals at the Paris Masters and here over the past three weeks have allowed the 32-year-old to look to 2014 with optimism.
Asked about his targets for next season, he said: “Winning five titles or something. Leaving the tournaments as a winner, that’s what keeps things exciting. Rankings; if it’s not world number one, then I’m not that interested.
“I think something’s possible for next year. I’m more positive now looking ahead than I would have been a few months ago where I wasn’t quite sure what to expect after the US Open.
“I’m back confident and excited going into the off-season and starting again next year.
“I need to make sure I stay competitive, that I can hang with the best, and particularly beat the best.”
Djokovic and Wawrinka had played two of the best matches of the year at the Australian and US Opens – the Serbian winning in five sets both times.
But Djokovic also won easily in Paris last week and, unfortunately for the packed crowd, this match was much more in that mould as the second seed ran out a 6-3, 6-3 winner.
It was a 21st straight win for Djokovic, and the defending champion said: “It was a very enjoyable match. The performance was definitely the best I had so far this tournament. It came in the right moment.
“It’s going to be a great final. I hope all the crowd will enjoy it because we definitely do on the court.
“It’s always a thrilling competition between me and Rafa.”
The signs for a close match were initially good as Wawrinka, who made it through to the semi-finals on his debut, produced some fine attacking tennis to break his opponent to lead 2-1.
But Djokovic hit straight back and the Wawrinka errors soon began to far exceed his winners.
It took Djokovic 50 points to hit his first winner but by then he was in control of the match, having shown his legendary powers of defence to break for 5-3.
Djokovic spent more than two hours on court on Saturday night winning a dead rubber against Richard Gasquet, but his appetite for another title was clear to see.
He saved a Wawrinka break point before clinching the opening set with his first ace and then broke again at the start of the second.
Wawrinka was under pressure in every service game but he withstood it until he served to stay in the match at 3-5, Djokovic clinching victory after an hour and 24 minutes.
Tonight’s final starts at 8pm.