Serena Williams' wait for a record-equalling 24th grand slam titles continues after former world number one Victoria Azarenka sensationally rallied to advance to the US Open final.

Stuck on 23 slam trophies since winning the 2017 Australian Open, losing four major finals since that last success at Melbourne Park, Williams looked on track to earn a 2018 US Open final rematch with Naomi Osaka after blitzing Azarenka in the first set.

But two-time major champion Azarenka completed a memorable comeback to prevail 1-6 6-3 6-3 on Thursday for her first slam final since the 2013 US Open decider, which she lost at Flushing Meadows.

Riding a 10-match winning streak having won the Western & Southern Open, a nervous Azarenka did not look like a player in form to start the match in a battle of the mothers.

Appearing in her first slam semi-final in seven years, Azarenka was broken in the opening game following two double faults and it was a sign of things to come against ruthless third seed Williams.

Committed to going big as she attacked Azarenka, a fast-starting Williams was unstoppable as the 38-year-old American superstar hit 12 winners and broke three times – closing out a lopsided first set on her opponent's serve.

Two-time US Open runner-up Azarenka, however, turned the match on its head in a high-octane second set under lights on Arthur Ashe Stadium in New York.

Out of rhythm in the opener, unseeded Azarenka settled after saving a break point in the first game of the second set.

Finding her range and eliminating unforced errors, Azarenka dug deep as the Belarusian earned a pair of break points, only needing one for a 3-2 lead before consolidating.

Azarenka produced a complete turnaround, reeling off 12 winners and a solitary unforced error against Williams, whose timing appeared off as the showdown went to a deciding set.

There was a worrying moment in the second game when six-time US Open champion Williams hunched over and required a medical timeout, re-emerging with a heavily strapped ankle.

Williams willed herself on, but Azarenka had all the momentum, breaking for a 3-0 lead and it was an advantage she never relinquished.

STATISTICAL BREAKDOWN

Azarenka bt Williams [3] 1-6 6-3 6-3

WINNERS/UNFORCED ERRORS

Azarenka – 24/17
Williams – 35/28

ACES/DOUBLE FAULTS

Azarenka – 2/5
​Williams – 6/3

BREAK POINTS WON

Azarenka – 3/7
​Williams – 3/5

FIRST SERVE PERCENTAGE

Azarenka – 68
​Williams – 65

PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE

Azarenka – 67/46
​Williams – 72/37

TOTAL POINTS

Azarenka – 80
​Williams – 78