This is incredible. Not sure I've ever seen a game go to deuce number 13. Anyone else remember one?

Sabalenka cooks up a backhand of brilliance - stretching out wide and thumping it crosscourt - to continue this slugfest.

But Raducanu is not to be deterred... and finally gets over the line! For the first time we see a real show of emotion from the Brit, who clenches her fist and roars loudly.

Many of the Cincy fans climb to their feet in appreciation at the determination and resilience of both players.

Raducanu''s first serve has suddenly gone walkabout and that's enabling Sabalenka to pile on the pressure.

The top seed brings up a fourth break point, which Raducanu inevitably saves.

Deuce number 12 (TWELVE).

Uh oh. Raducanu double faults... another chance for Sabalenka. The world number one goes long again...

Has Eastenders been and gone yet?

After all the graft, Sabalenka finally earns a second break point... then lumps a forehand long when a loopy return comes back.

Deuce number nine, deuce number nine. This is almost twice as long as Revolution No.9.

Sabalenka blinks with another loose return but Raducanu still can't tie it up.

Deuce number 10. Ridiculous!

Goodness knows how long this game has been. Far longer than a prog rock classic, for sure.

A seventh deuce goes Raducanu's way. She beats Sabalenka with a calm passing forehand when her opponent comes forward.

Advantage Raducanu... can she get over the line? Finally? No! A slow second serve is thumped crosscourt to safety by Sabalenka.

A wailing baby has been audibly for the past few minutes - leaving Raducanu exasperated.

"Do you want me to get it taken out," asks the umpire.

"Yes!" shout some fans. Raducanu chuckles.

Anyway, we're quickly back under way. A costly slice into the net from Sabalenka leaves the top seed dropping her racquet and screaming in anguish.

Then Raducanu doubles faults. It's all going on!!

Another first serve digs Raducanu out of a hole. That's been a major asset today.

She can't find another though and Sabalenka climbs all over her second serve with a return which pushes Raducanu back.

Deuce number six...

Again Raducanu edges ahead but again she is pegged back - this time by a sensational backhand winner the line from Sabalenka.

Rinse and repeat. The same exchange of points and we're into a FIFTH deuce.

This is starting to feel tense.

Advantage Raducanu becomes Advantage Sabalenka in a blink of the eye. Suddenly Sabalenka has let the tiger loose.

Raducanu saves the break point with a wonderful ace down the middle. Still there is little celebration.

Back to deuce...

Is the screw turning? Possibly. Sabalenka looks more locked in from the baseline as she moves 0-15 ahead.

But Raducanu remains calm, swatting away a forehand winner for 15-15 and then drawing another mistake from Sabalenka.

A first serve is followed by a confident backhand winner - with Sabalenka stranded - for 40-15.

But a double fault and a sharper Sabalenka dominating the next rally signals bad news for Raducanu. Deuce...

We've been waiting for the real Aryna Sabalenka to stand up - and finally she does.

For the first game in what feels like a long time, she looks like the world number one with a clean and efficient hold.

Not entirely sure how Sabalenka is ahead here.

Raducanu is playing very smartly. If you don't believe me, even Francisco Roig says so.

She is forgetting about the drama going on at the opposite side of the net, just letting Sabalenka do her own damage.

A woeful drop-shot bouncing before the net sums up Sabalenka's day. Another hold to love for the British number one.

Anyone willing to confidently pick a winner at this stage? Ufff, I sure ain't doing it.

If you're backing Raducanu, give us a thumbs up. And if you're thinking Sabalenka will escape despite being far from her best then hit the thumbs down.

Sabalenka's toils continue and she decides to go with a serve and volley. Interesting move.

Losing the point - and Raducanu forcing deuce - leads to the court getting the brunt of the Belarusian's frustrations.

Raducanu needs to keep calm and, er, carry on.

She can't make the most of a second serve, though, as Sabalenka moves to advantage - then a double fault brings it back to deuce.

Raducanu is a little tentative in the next point, too, helping Sabalenka drag herself over the line.

I might regret saying this, but... this is Raducanu's big chance against one of the world's stars. Sabalenka is nowhere near it.

Raducanu's first serve leads to Sabalenka batting a chipped forehand long for 40-30, then another laboured-looking return from the world number one hits the net.

Raducanu has served nicely so far - precisely and with purpose. She needs more of the same here.

Sabalenka swarms over her serve though to move 0-15 ahead, but then a wild return - closer to Row A than the baseline - brings it back level.

The boom and bust cycle from the Belarusian continues... a thunderous forehand rocking Raducanu before a weak backhand goes into the net for 30-30...

Raducanu reads the serve the right way - and the next ball - but can't get enough on the ball. Sabalenka saves it.

The top seed then moves to advantage, finally showing some energy and more positive emotion with a Tiger-like roar.

And here comes another as she drags herself over the line. That could be a pivotal moment.

Sabalenka's body language must be a confidence-booster for Raducanu.

A double fault from the world number one - her first of the match - leads to more shoulder slumping.

From 30-0, it is back to 30-30... and then Raducanu uses her backhand slice effectively to earn a break point...

Raducanu picks up where she left off in the second set with the ball in her hand. Another strong game ends in a hold to love for the British number one.