Naomi Osaka is doing such a great job of getting up the court and applying pressure.

She guides a winner into the corner for the hold.

Aryna Sabalenka will serve to stay in the set.

Naomi Osaka keeps the momentum going with an ace for 15-0. She gets to 30-0 when a stretching Aryna Sabalenka finds the tramlines as she looks to return a forceful Osaka forehand down the line.

A fifth forehand error from Sabalenka hands Osaka a 40-15 lead but a couple of mistakes from the Japanese mean it's not going to be a straightforward hold.

Felix Auger-Aliassime has taken the second set on a tie-break to level the match against Alejandro Davidovich Fokina.

I just looked at the clock and we're at two hours and two minutes, and there hasn't been a single break of serve yet.

This one has five-set marathon written all over it at the moment.

Image source, Getty Images

Amy Lofthouse
BBC Sport at Wimbledon

That second forehand from Sabalenka that she was broken on was horrible. She had all the time in the world and larruped it a mile over the baseline.

After a first service game hold to love, this has been poor from Sabalenka - and a beautiful display of controlled power from Osaka.

Sam Smith
Former British number one on BBC TV

She's missed it! The top seed is in big trouble early on out here.

Naomi Osaka has raced out to a 4-1 lead in this first set.

Aryna Sabalenka hasn't got her eye in yet and it's long again.

Naomi Osaka is racing through this opening set as the top seed is in a spot of bother.

Amy Lofthouse
BBC Sport at Wimbledon

I’d say it’s a bit too early for Aryna Sabalenka to be that annoyed with herself. That scream of frustration echoed around Centre Court.

The first signs of frustration from Aryna Sabalenka as she lets out a huge scream when putting into the net for 15-0.

Sabalenka channels those emotions in the right way and gets to 15-15 with an ace.

Sabalenka sets herself for a forehand and goes all in but it lands long to hand over another break point.

Tracy Austin
Two-time Grand Slam champion on BBC TV

Aryna Sabalenka is getting a little stuck. Naomi Osaka's shot awkwardly bounce so you have to have even better footwork than normal.

Naomi Osaka won't back down either, though.

A bruising forehand winner gets it to deuce and then she smashes a net volley for advantage.

Aryna Sabalenka is unable to get under a low ball on the baseline and hooks into the net.

Osaka comes through her first test with flying colours.

Advantage.

Aryna Sabalenka is refusing to let this game go without a fight.

Image source, Getty Images

Tracy Austin
Two-time Grand Slam champion on BBC TV

This match-up is just so interesting because the pair played back in 2018 and then they didn't play against each other for eight years, but this is the fourth they have played together this year.

It is going to be very different on grass though because it is such a low-bouncing surface. The flat ball Naomi Osaka hits really skids and stays low.

What her opponents are receiving is six inches lower off the forehand and backhand, that's going to make it difficult for Aryna Sabalenka with that extreme western grip.

Aryna Sabalenka is unable to capitalise.

Aryna Sabalenka should have the mental edge, she has won three of the previous four meetings with Naomi Osaka - including at the French Open in June. But this is the first time they have met on grass and Osaka is getting the better of these early exchanges.

Osaka gets to 30-0 but a double fault opens the door for Sabalenka. A lovely slice from Sabalenka sets up the opportunity to level and she takes it with a crushing forehand for 30-30.

A change to break back immediately.

Amy Lofthouse
BBC Sport at Wimbledon

These two are quite a contrast on court.

Sabalenka is all noise, and every emotion she feels goes across her face for good and bad. Osaka is much quieter, although there’s a fist pump towards her box after that early break.

Naomi Osaka is off to a flyer!

She cuts a lovely forehand and it skips away mid-court before Aryna Sabalenka can even consider trying to chase it.

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An early look at break point for Naomi Osaka when Aryna Sabalenka's forehand lands in the tramlines.

Beautiful and purposeful tennis from Naomi Osaka as she sends Aryna Sabalenka into the corner and steps into the court to smash away a winner for 15-0. There's some serious power on both sides of the court.

Sabalenka drops her sixth double fault of the tournament to trail 30-15 but comes up with an ace on her next attempt to level.

Osaka pushes Sabalenka all the way to deuce.

After losing the opening five points of the match, Naomi Osaka finally gets going as Aryna Sabalenka's forehand strays long.

Osaka forces Sabalenka deep behind the baseline to get the hold to 15.

There were a few issues in landing the first serve in that game for Osaka that she'll be keen to address sooner rather than later.

Image source, Getty Images

Felix Auger-Aliassime and Alejandro Davidovich Fokina's efficiency on serve continues as the pair reach another tie-break in the second set with neither playing dropping serve throughout the entire match so far.

Canadian third seed Auger-Aliassime had to navigate three set points in that last game but held his nerve brilliantly.

Spanish 22nd seed Davidovich Fokina is showing his frustration towards his coaching team.