Garbine Muguruza battled past Victoria Azarenka 6-4 3-6 6-2 to reach the US Open second week.
In the battle of the grand slam champions it was the Spaniard who raised her level when it mattered to reach the last 16.
She will now face Barbora Krejcikova or Kamilla Rakhimova on Saturday in the second week.
However it was last year’s finalist who drew first blood in this heavyweight clash of the titans after saving two break points, she went on the attack and broke for 2-0 using good angles on the backhand side.
The lead didn’t last long as Muguruza fought back and sealed the immediate break back as both players had success on return throughout the opening set.
Azarenka grew frustrated as the set wore on with Muguruza hitting some punishing forehands which cleaned the lines and produced remarkable depth on her grounstrokes.
The Belarusian would respond with some well constructed points and some clutch serving in crucial moments.
However it was Muguruza who was more efficient on her service games and it was her who gained the crucial break as she used her conserved energy to produce the perfect break to love.
The former Roland Garros and Wimbledon champion then sealed the set with an ace as she took the opening set in 49 minutes.
A quick response was needed from Azarenka to turn the momentum around and that was exactly what she did at the start of the second set.
Some perfect returns and aggressive forehands hit with pace forced errors from Muguruza as the Belarusian took a 4-0 lead.
The Spaniard controlled her game a little more to recover one of the breaks as 1-5 became 3-5.
Azarenka suddenly got tight on some big points with the Spaniard’s belief of a comeback starting to grow.
Although a couple of perfectly-timed drop-shots and a lucky net cord secured the set with a large roar following that as this match would go to a deciding set.
Both players started the match in tense fashion with both players saving break points en route to holding serve.
Eventually the quality of both players increased as the Arthur Ashe crowd witnessed some entertaining rallies.
The key moment was in the sixth game when Azarenka just wasn’t able to finish off her service game and was made to be punished for it as Muguruza broke in an eight minute game.
From then on it was the Spaniard who was in control as she held serve emphatically and broke again with accurate forehands to seal her place in the second week.
Another battling display from the world number one as she sealed her place in the last 16.
Next will be Barbora Krejcikova or Kamilla Rakhimova on Sunday.
