Welcome to live text updates of the second women's semi-final at the US Open between Serena Williams and Victoria Azarenka.

WILLIAMS 6-1 3-6 3-6 AZARENKA - IT'S ALL OVER! Azarenka wins through to the US Open with her first ever win over Williams, who suffers injury heartbreak at Flushing Meadows. She will be absolutely gutted about sustaining that ankle injury in the final set, but Azarenka deserves her victory and will take on Naomi Osaka in the final on Saturday.

WILLIAMS 6-1 3-6 3-5 AZARENKA - Williams does all she possibly can and serves out to leave Azarenka with the stage to see if she can hold her nerve and close out this match to reach the final.

WILLIAMS 6-1 3-6 2-5 AZARENKA - What a performance from Azarenka, who battles through another hold with Serena throwing everything at her, and she is now just one game away from reaching the US Open final.

WILLIAMS 6-1 3-6 2-4 AZARENKA - Williams again shows incredible heart to come through and win another service game under pressure from Azarenka and coping with that ankle injury.

WILLIAMS 6-1 3-6 1-4 AZARENKA - Azarenka senses that this is her time and races through a service hold to extend her lead once more in this final set. Does Serena have anything left with that ankle?

WILLIAMS 6-1 3-6 1-3 AZARENKA - Serena is in a world of pain on that ankle, but she courageously comes through a service hold to at least get on the board in this final set.

WILLIAMS 6-1 3-6 0-3 AZARENKA - Azarenka consolidates her break of serve, and now she is cruising in this third set. Williams is going for broke in every point, trying to keep the rallies short with her ankle injury.

WILLIAMS 6-1 3-6 0-2 AZARENKA - BREAK! Williams' ankle is now being supported by the most enormous, almost cast, of strapping. It must be very difficult for her to move out there with all that tape, and Azarenka breaks.

WILLIAMS 6-1 3-6 0-1 AZARENKA - Oh dear! Serena is not looking to be in a good way as she struggles with an apparent ankle injury and she does not seem at all happy. She will now receive some medical treatment on court.

WILLIAMS 6-1 3-6 0-1 AZARENKA - Azarenka serves first in this deciding set, which could be an advantage, and she produces a fine opening game to get on the board. She is very fired up!

WILLIAMS 6-1 3-6 AZARENKA - SET! After an hour and 13 minutes, we are into a deciding set! Azarenka has shown incredible resilience to respond in this match, and now this could go either way.

WILLIAMS 6-1 3-5 AZARENKA - It's a really tough service game for Azarenka, but she battles through very impressively under enormous pressure from Williams. After a long deuce, she wins the game.

WILLIAMS 6-1 3-4 AZARENKA - Williams holds to reduce the deficit and she is not going to let this second set run away from her without a fight.

WILLIAMS 6-1 2-4 AZARENKA - Very impressively, Azarenka consolidates her break of serve with a battling hold, and now she has control of this second set.

WILLIAMS 6-1 2-3 AZARENKA - BREAK! Azarenka produces two brilliant forehands to really do the damage on the Williams serve, and she breaks to 15 to seize control of the second set.

WILLIAMS 6-1 2-2 AZARENKA - Azarenka holds to keep pace with Williams, and this second set is already much more competitive and intense than the underwhelming opening set.

WILLIAMS 6-1 2-1 AZARENKA - We've still only played 46 minutes in this match, which is remarkable considering where we are. Williams holds after deuce with Azarenka having upped her level.