Williams beaten by Azarenka in US Open semi-final

Serena Williams had been seeking to equal Margaret Court's record of 24 Grand Slam singles titles

Venue: Flushing Meadows, New York Dates: 31 Aug-13 Sept
Coverage: Selected live radio and text commentaries on BBC Radio 5 Live Sports Extra, BBC Sounds, the BBC Sport website and app.

Serena Williams' latest bid for a 24th Grand Slam singles title ended as Victoria Azarenka rolled back the years to reach the US Open final.

The American called on the trainer for an ankle problem early in the third set and struggled physically after that.

Belarusian Azarenka faces Japan's 2018 champion Naomi Osaka in the final.

Two-time Australian Open champion Azarenka had been appearing in her first Grand Slam semi-final since 2013 following troubled times on and off the court.

But she has been in fantastic form in recent weeks, having now won 11 matches in a row after victory in the Western & Southern Open just before the US Open.

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An old rivalry rekindled

Williams and Azarenka were once regular opponents on the biggest stages - but this was their first encounter in the latter stages of a Grand Slam since a Wimbledon quarter-final in 2015.

The two good friends have had maternity leaves since then and Azarenka's career was also stalled by a lengthy custody battle over her son.

Williams had dominated their head-to-heads, winning 18 of their 22 encounters until now, including back-to-back wins in the 2012 and 2013 US Open finals. And until now she had won all 10 of their Grand Slam matches.

But that record was from a different time - in this match the stakes had changed, and so had the players.

Williams has for some time been carrying the pressure of the personal desire and the public expectation of a matching Margaret Court's titles, while Azarenka is playing with a new freedom that has come only recently since she admitted she was finally enjoying her sport having "taken the fear of failing away".

It had looked like Williams was in control of the match, racing through the first set in ruthless fashion in 35 minutes, but a missed backhand to put her 2-0 up in the second set marked the beginning of a change in tide.

When Azarenka launched a blistering backhand winner cross-court to break for 3-2 and then followed that up with a hold to love, the match became an encounter of the highest quality.

Williams' screams got louder but her intensity dropped and a forehand into the net gave the Belarusian two set points, the first of which she converted.

The American, who had played three back-to-back three-setters coming into this, then needed treatment on her ankle while trailing 1-0 40-40 in the third set.

While Williams had a vast amount of strapping applied, Azarenka sat with her eyes closed meditating in her chair.

She kept calm to break immediately on the restart and eventually sealed victory with an ace - via a desperate Hawk-Eye challenge from Williams, whose next opportunity for a Grand Slam title comes later this month at the rescheduled French Open.

"I needed to find energy to climb out of the hole and it wasn't easy," Azarenka said. "Hopefully it inspires women to go after their dreams, they can do anything."

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