In a gripping 4-hour 49-minute contest which concluded at 2.04 a.m. on Wednesday, world number one Nadal won through to keep his bid for a fourth title in NY and 18th Grand Slam crown on track. Nadal's ability to look only forward and forget what went before is one of his most important strengths and he set about turning around the match, closing in on the baseline, forcing Thiem to play one more ball and, eventually, to go for too much.
In an interview after his titanic battle, the 32-year-old Nadal gave credit to his opponent saying the match was very demanding in all aspects after almost five hours on court. "It was a real battle".
"It's been a great battle, the conditions were tough, a lot of humidity". For me it was...
"He has plenty of time to win big tournaments and has everything".
Thiem told a post-match media conference: "It's going to be stuck in my mind forever". It's cruel sometimes tennis, because I think this match didn't really deserve a loser. Some patented Nadal scrambling forced Thiem to take one more swing, an overhead, and the 25-year-old Austrian pulled it long. "It was a very tough start, I tried to stay in the match in the second set", he said on court after securing passage to the semifinals.
Nadal could easily have wrapped it up in the fourth set and missed five break points in the decider, but found a way to take one last opportunity against Thiem and his flowing single handed backhand.
Nadal, facing his fellow seed away from clay for the first time after 10 previous meeting, was 30-29 when losing the first set at a major, but he rediscovered his best form to level the match, rising to the challenge by converting both break-point chances - having earned none in the first set - to halt the red-hot Thiem. I didn't want to come back out'.
This was tennis at its absolute best, according to David Law (BBC 5 Live) and Catherine Whitaker (Amazon Prime Video), and also a brilliant advert for fifth set tiebreaks.
Meanwhile, Serena Williams survived a scare from giant-killer Kaia Kanepi to claim a roller-coaster 6-0, 4-6, 6-3 win and move a step closer to a record-equalling 24th career Grand Slam title.
"He has a great attitude and is a great fighter".
"I am the guy to look at myself", Nadal said.
"(I am) sad for him because when [he arrived at] this moment, he did all the things well to win the match.
Nadal will now meet Argentine and world number three Juan Martin del Potro in the semi-finals, but the 32-year-old revealed the conversation he had with his Austrian opponent Thiem. "I like this feeling, but at the same time you feel exhausted after that", Nadal said.
Nadal won just seven points for the entire set, his nine unforced errors handing the set to Thiem on a plate. But the last time, against Philipp Kohlschreiber in Miami last spring, he fought back to win the match. "I hope that it's a little bit more comfortable on hard courts, but I'm not sure". And, yes, I played against a great opponent.