American teenagers Coco Gauff and Caty McNally moved into the US Open women's doubles final after Luisa Stefani of Brazil unfortunately suffered an injury during their first-set tiebreak and was forced to retire from their semifinal.

No.11 seeds Gauff and McNally advance into their first Grand Slam final, with the final score over No.5-seeded opponents Stefani and Gabriela Dabrowski of Canada as 6-6, ret.

Gauff and McNally will face the veteran pairing of Samantha Stosur of Australia and Zhang Shuai of China for the US Open title.

No.14 seeds Stosur and Zhang, the 2019 Australian Open champions, defeated No.7 seeds Alexa Guarachi of Chile and Desirae Krawczyk of the United States, 6-2, 7-5, in the earlier semifinal.

Very little separated Gauff and McNally from Dabrowski and Stefani in the first set. Dabrowski and Stefani had come into the US Open in fine form, having gone 16-2 since pairing up at the start of the summer, including a title in Montreal.

But the Americans matched the No.5 seeds shot for shot at the net, coming back from a break down to level the match at 3-3. Gauff and McNally had the first opportunities to clinch the opener, holding four set points on the Dabrowski serve at 5-4, but powerful, aggressive play by the Canadian-Brazilian pair allowed them to fend the quartet off.

After a pair of love holds by each team, they moved into a tiebreak, where Dabrowski used a deft lob to force an error -- a tactic which had been working for her team regularly during the match -- to grab an early mini-break.

But with her team leading 2-0 in the breaker, Stefani turned her leg mid-point at the net and fell to the ground in obvious pain. The Brazilian attempted to walk off the court, but had to be taken off in a wheelchair, and the match immediately came to an unfortunate conclusion.

"Luisa’s such a great doubles player, and as a team they're very difficult to play," McNally said on court, after the match. "I think this match was going to be such a great match, anyone could have taken the first set. I hope that she’s okay and that she’ll recover quick, and it’s never the way you want to win."

"For me, I don’t want to win a match like this," Gauff added. "Luisa’s so nice and I cannot watch that again, because it’s so hard to see another opponent finish a match like that....I wish her the best wishes, and as an athlete, you know how an injury like that is just heartbreaking, and I think that we should just all come together and support her."

Stosur and Zhang, meanwhile, are on a big winning streak, having triumphed in their last 10 matches. In their previous event, they defeated Dabrowski and Stefani in the Cincinnati final.

In Louis Armstrong Stadium, long-time friends Stosur and Zhang defeated Guarachi and Krawczyk in 72 minutes to reach their second major final as a team.

Zhang's only Grand Slam title thus far came with Stosur two years ago in Melbourne. Stosur has already won three Grand Slam women's doubles titles in her career, including a US Open way back in 2005 alongside Lisa Raymond.

Stosur and Zhang took over the first set early, after fantastic forehands by Stosur steered them to a break of Guarachi for 3-2. Two games later, the pair broke Krawczyk at love for good measure, completing that game with a Stosur backhand return winner. Zhang then served out the set at love.

The 14th seeds romped to a 5-1, double-break lead in the second set, but Guarachi and Krawczyk fought back, breaking Zhang, who was serving for the match, to pull within 5-3. After a love hold by Guarachi, Stosur served for the match, but slammed her team's first double fault on break point, and the match was tied at 5-5.

But a grueling game went the way of Stosur and Zhang as they broke again for 6-5, thanks to an error-forcing crosscourt backhand by Zhang. With her squad serving for the match for a third time, Zhang made no mistakes, hitting an ace to complete a love hold.