A whopper of an ace down the middle leaves Raducanu flat-footed.

Five set points to Sabalenka...

Further daylight and you can't imagine Sabalenka will choke this now...

Uh oh. The pressure tells on Raducanu. A double fault puts Sabalenka well in command.

Boom! That is classic Sabalenka. She moves Raducanu around before setting herself to swat away a clean inside-out forehand winner.

Sabalenka has not lost a first tie-break this year. Just saying.

Another second serve... it's a brave one and draws Raducanu into a mistake.

Sabalenka's second serve is pounced on by Raducanu's backhand, leaving the Belarusian scrambling and unable to turn the point around.

Raducanu serves first... and sprays a forehand out of the court. Argh.

And, just as easily, Sabalenka holds to love.

Pressure? Pah. The world number one maintains her position about half a metre behind the baseline and dominates the rallies to send us into a tie-break.

Very good, very good.

Raducanu rattles out a hold to love, creating angles which remind me of trigonometry classes back in the day and serving with a solidity which Manuel from Fawlty Towers can only dream of.

Sabalenka, for the second time, has to serve to stay in the opening set.

Calmness is the key word in the Roig's coaching manual, it seems.

Raducanu has thrived this season with a new sense of tranquillity, so it makes sense that the Spaniard continues in the same vein.

Sabalenka is rarely calm for long. She demonstratively slumps her shoulders and gestures to her team - you know the body language.

This comes after she holds. Back to Raducanu...

Again, Raducanu resets admirably and is able to drag herself over the line to level.

A lot of conversation going on between Raducnau and Roig - including after the ninth game.

She jogs over to the box and receives more instructions from her new coach, who gets up to go closer and offer more advice.

That lands Raducanu in trouble with the umpire.

Far from job done though. Raducanu needs to hold her nerve - and her serve.

A double fault allows Sabalenka back in at 30-30 and before she knows it is facing another break point.

But the first serve acts as a shovel - digging her out of a hole and back to advantage.

Hold on... Sabalenka isn't ready to roll over. Thumping balls back and forcing a stretching Raducanu into a loopy return which goes long.

Back to deuce...

Well, well.

Raducanu refuses to be too disheartened, sticks to the task and gets her rewards.

The British number one locks into a baseline rally and takes the second break point when Sabalenka crunches a forehand into the net.

"Vamos!" shouts Roig.

What is Sabalenka up to here?! Bizarre. She stops playing, presumably because she thinks she has served a double fault, and tries to hit the ball behind her back.

Two break point for Raducanu...

"You have to be brave - and calm," shouts Raducanu's new coach Roig.

Sound advice.

Raducanu's aggression has dropped from the start of the match, but she ups the RPMs and goes for the margins to force mistakes from Sabalenka.

Another Sabalenka returns misses the court and she is 15-30 down...

Raducanu has come up way short of the very best players in the past few years - at least until she pushed Sabalenka at Wimbledon.

She's under serious pressure now and if this service game slips out of her grasp then it could get ugly.

From 30-30, the game could go either way... but Raducanu resets mentally to find her first serve and ensure she is just a single break down.

Further daylight between Sabalenka and Raducanu as the world number one holds serve with minimum fuss.

Raducanu was level at 30-30 but Sabalenka's tactic of coming forward more and taking time away from the Brit is working a treat.

Not good news from the Champions' Court next door.

France's Arthur Rinderknech has retired from his match against Felix Auger-Aliassime after struggling in the hot conditions.

He resumed playing after falling to the court, but still looked light headed and unsteady on his feet.

Looks like he made the right call to stop.

That's why Sabalenka is the world number one, eh?

A positive start by Raducanu is quickly forgotten about and she goes through from first to fourth gear in a matter of minutes.

Interesting to hear Francisco Roig's observations from the Raducanu box.

With a microphone in front of him, we can hear him urge some spinny kick serves at 15-30 before a message of "Vamos, good" indicates he is happy.

Back to 30-30... but Sabalenka brings up another break point with a hefty forehand and then smacks a backhand winner for a third game in a row.