When Thiem finally broke down, with a botched smash on match point, the clock showed 2.04am in NY and the match duration was 4 hours 49 minutes, making it Nadal's longest ever match at Flushing Meadows.
In a dramatic final set, Nadal saw five break points come and go before Thiem went long with a smash on the first match point.
In a battle between two gladiators, bot of whom refused to give up, World No. 1 and defending champion Rafael Nadal emerged unscathed, but not before he and Dominic Thiem gave the world a delectable display of high-quality tennis.
Nadal will face third seed Juan Martin Del Potro in the first of the semi-finals at Flushing Meadows.
The Austrian blasted 13 winners, made only two unforced errors and allowed Nadal just seven points in winning an extraordinary opening set.
The six-time US Open champion, who missed the tournament a year ago and gave birth to her daughter during it, advanced to face 2016 finalist and No 8 seed Karolina Pliskova. This sport is tough, so it's so easy to get very frustrated out there on the court when things aren't going your way. For Mickelson, more than setting a record by playing his 12th Ryder Cup, the 48-year-old gets what he believes will be his last chance to capture that gold trophy away from home.
The longest match of the US Open so far saw top seed Nadal comprehensively beaten in the opening set, before showing all his enormous reserves of fight and spirit to knock out the ninth seed. Thiem, energized after extending the match, held serve to start the set, while Nadal had brushed off the signs of discouragement from the end of the fourth.
4 updates coming to Google Chrome for its 10th birthday
Users can even add the search bar to the bottom of the page in iOS and can enjoy general simplification of the menus in Chrome . And finally, in terms of new up front features, Google is letting you customize the new tab page with your favorites.
The top-ranked Nadal captured his 11th title in Paris by beating Thiem in straight sets in June.
"The conditions were tough, a lot of humidity". He hit 19 winners in the fourth set-which was an 81-minute mini-classic all by itself-and won it in a tiebreaker.
He fell behind by a break in the third set before rebounding.
He walked quietly to the center of the court, then stepped over the net and embraced 25-year-old Dominic Thiem. After that first set, then the match became more normal.
The Austrian was often in the driver's seat and closed out points against Nadal, the best defender in the game, with his backhand.
"'Wake up, '" Nadal said he told himself.
Nadal was clearly rattled and lost the first three points of the tiebreak that Thiem won 7-4 to force a fourth set.
Nadal said that losing the first set by 6-0 was not in his plan but he accepted it with "humility", while in the fifth he had "more options" than Thiem.