"They came out really aggressive, and we weren't really hitting the spots," Mirza explained during their post-match interview. "We lost that second game, which, I thought, was crucial; if it was 1-1, it was a completely different game.
"The thing is that, we both know that if we make a few, we can always come back, and obviously that's what happened. The crowd got us going too, today; they were really behind us every point. We felt the energy, so thanks guys!"
The Chan sisters had split their last two meetings with Hingis and Mirza - beating them just before the fortnight began at the Western & Southern Open - but they saw their lead evaporate as quickly as it had appeared with the top seeds' rapid improvements.
"At 5-0, all I said was, 'let's just get two games and try to get some rhythm for the second set,' and before we knew it, we were 5-5. I think tennis is an amazing sport. It gives you so many chances, it takes away so many chances too. We played a couple of big points at 5-3 to break her. At 30-all I made one return winner, [Martina] made one return winner, and that was it."
Hingis is hoping to reach a second straight US Open final and her first with Mirza; the two have been nigh unstoppable since pairing up this spring, winning titles in Indian Wells, Miami, and Charleston before Grand Slam glory finally came at the All England Club.
"We know they're great opponents and I think definitely whoever wins this match deserves it," the Swiss Miss said of her mindset before the match. "We've had matches like that against them, that we were down, and fought back, and were able to win. That's why, even try to get on board in the first set and it just kept clicking. Sania kept me alive in the first set; everything was happening so fast!"
Up next for Hingis and Mirza are the all-Italian No.11 seeds, Sara Errani and Flavia Pennetta, who battled back from a second set lull to outfox the No.15 seeded team of WTA Rising Star Lara Arruabarrena and Andreja Klepac, 6-0, 5-7, 6-2. Errani won the US Open in 2012 with Roberta Vinci(now in the singles semifinal), while Pennetta reached the final with Hingis last year - beating Mirza in the semifinals. Hingis is all too aware of the role reversal.
"Coming off the Wimbledon win, we're the favorites to play here in the US Open. I made finals, [Sania] made semifinals, so we're in the same spot from last year. We'll face a tough team with Errani and Flavia Pennetta - she was my partner last year, so now we are on the opposite sides, so it will be interesting!"
Hingis is also still alive in the mixed doubles event, which completed its quarterfinal matches on Tuesday. First up on Louis Armstrong Stadium was the unseeded pairing of Andrea Hlavackova and Lukasz Kubot, who edged past Anastasia Rodionova and Max Mirnyi, 6-4, 6-4. Hlavackova won the mixed doubles title in Flushing with Mirnyi in 2013 - along with the women's doubles crown alongside Lucie Hradecka - and is feeling confident with a potential second mixed title in sight.
"We really had tough opponents, all the matches we played with Lukasz," she told the crowd after her win. "We're really supporting each other and playing very well, so I guess it is the best tennis!
"I really feel a lot of power from [Lukasz]. He serves amazing, he returns big. I like that game style so it really makes me play better on the court when I know that my partner can do those things."
Hlavackova and Kubot will play the winner of the last quarterfinal between Bethanie Mattek-Sands and Sam Querrey and No.6 seeds Yaroslava Shvedova and Juan Sebastian Cabal, which got underway later in the afternoon.