It was a mixture of relief and joy from the Serb at the end of four hours and nine minutes of unrelenting sporting theatre.
The fact that the world No 1 eventually booked his place in his fourth consecutive US Open says everything about his indomitable, battling spirit and refusal to wilt when the heat is searing on his shoulders.
But for Wawrinka, who came within a whisker of beating Djokovic in Australia this year before falling at the last, there was only abject disappointment and the lingering feeling of what could have been.
Twice he led, twice he was pegged back by this incredible warrior, who eventually dug out a 2-6, 7-6, 3-6, 6-3, 6-4 triumph. He is the greatest player on planet tennis for a reason. The mental strength, the ability to stand firm at key points set the 26-year-old apart.
This wasn't him at his best - Wawrinka, Andy Murray's conqueror, had much to do with that - but he still had enough. Yet you would struggle to find anyone here who didn't have a place in their heart for the world No 10. What a performance from the Swiss who, despite his Herculean efforts, exits New York with pride but nothing more. The relief, meanwhile, poured out of the Serbian as appreciation was shown from all sides of this tennis ampitheatre at Flushing Meadows.
"These matches are what we live for," said Djokovic. "He played more aggressive and was playing better me. I was trying to hang in and adjust. I am just fortunate to play my best tennis when I wanted to."
Wawrinka tried to look on the bright side while feeling the agony of losing the classic encounter. "It's a strange feeling, but for me I think I need to take the positive again of that loss. It's my first semi-final in a Grand Slam, so I had a great tournament. Unfortunately today I was a little bit struggling physically.
"I had the feeling when I was still fit, when I was still healthy I had the match in control. I think I was playing better than him. I was doing much more things than him. But he's not No 1 for nothing. He was staying with me all the match, and at the end he pushed me far, far, far back. I had to find everything I had in my body today to stay with him, and he won the match."
Wawrinka may have been playing in his first Grand Slam semi-final, yet he rose magnificently to the challenge. The quality of his groundstrokes brought gasps from a capacity crowd at Arthur Ashe stadium.
Djokovic was appearing in his 14th straight major semi-final. That is only second behind Roger Federer, who is close to becoming Switzerland's second best player.
The first set was over in just 34 minutes and its brevity left the Serbian shell shocked. A break for 2-1 helped Wawrinka gain early control, a double fault from the normally unflappable world No 1 before a smack into the net sealed it.
Djokovic was starting to melt in the afternoon sun, growling to his box, at odds with himself - most notably on his serve. Another loose double fault gave Wawrinka another opportunity, one gleefully gobbled up by the Swiss who unleashed a fierce forehand to extend his lead to 4-1.
It was an awesome display from Wawrinka. Almost inconceivably, the Serb looked nervous. Wawrinka had nothing to lose - and it showed. He managed to claw one break back only to hand the advantage straight back, more double faults leaving the world No 10 to serve for a one-set lead, which was sealed with an ace.
It was a shock to see Djokovic on the end of such a pummelling. Yet having seen Wawrinka reach this stage with growing stature, there was somewhat of a predictable feeling about it. But when Djokovic is contesting majors, giving up without a fight is not an option. He was applying the pressure to the Wawrinka serve, the Swiss saving three break points to get to 2-2 and when the world No 1 hit long, another break was in the bag.
That the was the cue for Djokovic to get angry. A ticking-off from the umpire for a coaching violation didn't help his mood. Yet the fires were burning inside this gladiator. The 26-year-old is athleticism personified, an astounding get from a superb Wawrinka angled volley summing up his force of will.
So we went to a tie-break. And as the nerves began to weigh heavy on his shoulders, Wawrinka's level dropped. A looped forehand sealed the set for Djokovic. It was level pegging and impossible to call.
The next two sets were a microcosm of the first two. A break from the Swiss at 4-3, a quite brilliant game which he won to love, set the platform for him to take the third set which saw an astounding 35-shot rally end with Djokovic smacking the ball into the net and falling behind once more.
Back, though, came the reigning Australian Open champion. A double fault allowed him to take an early 2-0 lead and when the Swiss assaulted his racket with a swipe of pure anger, you knew a fifth set was in the offing.
The pressure was relentless. Wawrinka saved four break points at 1-1, a stunning back-hand winner to rescue the fourth showed he was far from dead. Six game points went begging - the third game ticked over to a mentally sapping 21 minutes until the Swiss finally held firm.
It was a monstrous hold. But in the fifth, a Djokovic backhand sealed a break for 4-2. A strong hold to love showed Wawrinka was still alive. But now came the moment of truth. Djokovic was serving for a place in tomorrow's final. It was break or bust for the Swiss, but the guy at the other end, a player who just refuses to die served out with aplomb. Was it really in doubt?