Karolina Muchova and Jakub Mensik saved two match points on their way to the US Open mixed doubles title and $1m in prize money.
Mensik hit a 131mph ace on a third championship point to seal a 6-3 1-6 10-6 win in the final against Belinda Bencic and Flavio Cobolli.
That victory came after they saved match points in their semi-final against Andrey Rublev and Mirra Andreeva.
It is a first Grand Slam title for both players and comes just over six weeks after Muchova was beaten by compatriot Linda Noskova in the Wimbledon final.
The 30-year-old has been out of action since after undergoing a "small surgery".
Mensik, a semi-finalist at this year's French Open, had never played mixed doubles before, but his serve more than made up for his inexperience.
The pair had agreed to wear matching maroon outfits on court - once Muchova had explained to her 20-year-old team-mate what the colour was.
"It's not probably the main fact that we won the title, but that we had really great matches to play," Menik said.
"It's good we tried a lot of things on the court. It gives you a little bit of boost of confidence."
Both semi-finals were decided by a 10-point tie-break. Bencic and Cobolli won the first 10-5 against Elina Svitolina and Gael Monfils, denying them the opportunity to become the first married couple to win a Grand Slam mixed doubles title since 1939.
They will not have another chance, as Monfils is retiring at the end of the season.
Muchova and Mensik then held off French Open champion Andreeva and Rublev in the second semi-final to win 5-4 (8-6) 3-5 11-9.
All eight semi-finalists will be contesting the US Open singles main draw, which gets under way on Sunday.
This reimagined version of mixed doubles will never be to the liking of those who struggle with the concept that a Grand Slam title can be decided in under 48 hours.
But there is no question it now commands more attention from a global audience.
Instead of the mixed doubles primarily being an event for grounds pass holders, the semi-finals and final were played under the lights in the night session, ensuring a much bigger television audience.
Even with the introduction of a qualifying competition this year, specialist doubles players still have limited opportunities in an event now built around the singles stars.
But those who do make it into the draw are competing for a prize that is five times what is was under the old format.
And the prize pot for the men's and women's doubles - still very much the preserve of the specialists - has also jumped significantly to match what is on offer in the mixed doubles.
Singles players enjoy the format and the chance for an early feel of the show courts, but the tournament will never be a priority for them.
Iga Swiatek, Frances Tiafoe and Daniil Medvedev all pulled out shortly beforehand - the first two as they needed rest after a successful spell on tour, and the latter as he felt he needed more matches before the US Open.
But if the United States Tennis Association can attract pairs of the calibre of Serena Williams and Carlos Alcaraz, as well as Aryna Sabalenka and Novak Djokovic, they will consider it a success.
The mixed doubles is just one part of an ever-expanding 'Fan Week' at the US Open.
Roger Federer featured in an exhibition with Andre Agassi, John McEnroe and Andy Roddick on Tuesday, with Amanda Anisimova and Alexandra Eala among the cast for the 'Stars of the Open' on Thursday evening.
And all this after The Lumineers officially kicked off the US Open with a gig inside the Louis Armstrong Stadium last Friday night.
That is a full nine days before the main draw actually gets under way.
