Karolina Muchova and Jakub Mensik produced a remarkable comeback to reach the mixed doubles final in New York, while Belinda Bencic and Flavio Cobolli also fought back to keep their perfect record as a partnership alive.
The Czech pairing appeared to be heading for defeat after falling 3-0 and 8-5 behind and then facing two match points. Instead, Muchova and Mensik held their nerve in the biggest moments to turn the match around and book their place in the final.
They defeated Mirra Andreeva and Flavio Cobolli 4-5 (7), 4-1, [10-5] in a dramatic match tiebreak. Muchova's creativity at the net and Mensik's powerful groundstrokes and serve once again proved to be an effective combination.
Muchova made an important contribution early in the contest, producing a volley winner to close out a tense opening set. The pair then lost the second set despite holding a break advantage, leaving the match to be decided by a 10-point tiebreak.
That was when Mensik stepped up.
The 20-year-old repeatedly relied on his powerful serve to keep the Czech team alive. His biggest moment came when he saved a match point with a huge serve to level the tiebreak at 9-9.
He followed it with another unreturnable delivery to put Muchova and himself on match point before the pair won the final four points to complete the comeback.
Their victory sends them into the final with plenty of momentum, but they will face another team that has yet to lose as a partnership.
Bencic and Cobolli also had to recover from a difficult start in their semifinal. After dropping the opening set, they found themselves 1-0 down in the second and facing three break points.
The pair saved all three opportunities before taking control of the set, winning the final four games to force another match tiebreak. They then maintained their composure at the net to finish the comeback and secure their place in the championship match.
The result extended Bencic and Cobolli's record to a perfect 7-0 as a team. They have also dropped just two sets throughout the tournament, setting up an intriguing final against Muchova and Mensik.
The championship match will also feature a different format from the earlier rounds. While matches throughout the tournament have been played with sets to four games, the final will use full sets to six games.
If the match goes to a deciding set, it will not be played in full. Instead, a 10-point tiebreak will determine the champions.
There is also a major financial incentive on the line. The winning team will collect a $1 million prize, adding even more significance to a final that already promises to be closely contested.
Muchova and Mensik will now look to complete their remarkable run with another victory, while Bencic and Cobolli will aim to preserve their unbeaten record and claim the biggest prize of the tournament.
