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Defending champion Carlos Alcaraz beats Tommy Paul 5-7 6-4 6-2 6-2 to reach semi-finals
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Sun 7-5 3-5 Vekic*
Here comes Donna Vekic... it's come from nowhere but the Croat has the break in the second set.
She let out a cry of delight when getting it to 15-all and really seemed to up it for the set of the game.
Lulu Sun will have to respond in the next game otherwise we're going to a deciding set...
*Sinner 6-6 (3-3) Medvedev
A double fault brings Jannik Sinner a mini break back - was Daniil Medvedev feeling the effects of the rally on the previous point?
Sinner wins the next point on serve as Medvedev goes into the net.
*Sun 7-5 3-4 Vekic
The way these two are serving at the moment, a tie-break is beginning to feel increasingly inevitable.
It only takes one off game to change that, of course, but for now - after another simple hold for Donna Vekic - it stays on serve.
Sinner 6-6 (1-3) Medvedev*
A mini break for Daniil Medvedev as Jannik Sinner puts a forehand wide.
The Russian follows it up by winning an epic rally - 33 shots that was!
Some deep breaths from the Russian after that.
Sun 7-5 3-3 Vekic*
Lulu Sun has won every first serve point on her serve so far in this second set.
An ace down the T means she's nine from nine.
Donna Vekic has won seven of eight after getting her first serve in and every point on her second serve. So where are these break chances coming?
Sinner 6-6 Medvedev*
Shot of the match so far from Daniil Medvedev? A big forehand lands right in the corner to bring the Russian to 0-15 as the crowd ooh and ahh.
A lucky bounce off the net then sees the Russian get to 40-30 before Jannik Sinner's trusty first serve sees the Italian hold.
Tie break time.
*Sun 7-5 2-3 Vekic
Donna Vekic holds with ease again.
It's not dissimilar to the first set when Lulu Sun wasn't able to make much headway against the Vekic serve - until she was.
Sun was the more ruthless when her chance came and that is why she's a set to the good.
Sun takes first set against Vekic
Jonathan Jurejko
BBC Sport at Wimbledon
Guess who's back? Back again. Djoko's back... in the evening slot on Centre Court.
After last night's drama, where he bit at the SW19 crowd for what he claimed were boos towards him, Novak Djokovic returns to play Australia's Alex de Minaur in his quarter-final tomorrow.
Elena Rybakina, the red-hot favourite for the women's title, plays Ukraine's Elina Svitolina when play starts on Centre at 13:30 BST.
Over on Court One, Latvia's Jelena Ostapenko plays Czech Barbora Krejcikova in the opening match at 13:00 BST.
After that is the men's quarter-final between American Taylor Fritz and Italy's Lorenzo Musetti.
Sun 7-5 2-2 Vekic*
Still on serve, there is not even an inkling of a break opportunity so far in the second set.
Donna Vekic's cleanly-struck forehand is the only thing that prevents Lulu Sun holding to love.
*Sinner 5-6 Medvedev
A long backhand from Daniil Medvedev brings the score to 30-30 before a big first serve gets him to game point.
A Jannik Sinner backhand goes into the net and the Russian holds.
*Sun 7-5 1-2 Vekic
Joe Rindl
BBC Sport at Wimbledon
The rain is hammering against the Court One roof.
It's all you can hear at the moment.
Sinner 5-5 Medvedev*
Emily Salley
BBC Sport at Wimbledon
This first set is too close to call between Jannik Sinner and Daniil Medvedev.
We haven't seen a single break point and a tie-break is looking inevitable.
The crowd also seem to be struggling to make up their mind on who to support - it's all very civilised at the moment.
Sinner 5-5 Medvedev*
Jannik Sinner is yet to drop a point when he gets the first serve into play and it's another quick hold to love for the Italian top seed.
*Sun 7-5 1-2 Vekic
All very straightforward for whoever is on serve early in this second set.
Donna Vekic hammers a serve down the middle to go up 40-15 and closes it out with a serve out wide.
*Sinner 4-5 Medvedev
Todd Woodbridge
Former Wimbledon doubles champion on BBC TV
Darren Cahill (Jannik Sinner's coach) is a terrific coach. He makes sure his athlete is in a good frame of mind and a good place off the court. That’s what he does so well.
The one thing he could add to Sinner is a slice backhand to get him pushing forward. It’s just about nuances and adding more.
*Sinner 4-5 Medvedev
Daniil Medvedev is also making the most of the new balls with a couple of big first serves, including an ace.
The Russian holds.
Cameras show some excited fans out on Henman Hill holding umbrellas. It's giving muddy festival vibes.
Sun 7-5 1-1 Vekic*
Brilliant from Lulu Sun.
The serve is out wide, Donna Vekic returns cross-court and Sun steps into it and hammers a winner down the line.
A comfortable hold to 15 for the world number 123.
*Sun 7-5 0-1 Vekic
That will be a confidence booster for Donna Vekic.
She looked the more likely to break for much of that first set but saw it slip away from her.
A hold to love is a nice settler for the Croat to start the second.
Sinner 4-4 Medvedev*
New balls does the trick as Jannik Sinner powers through his service game for a straightforward hold to love.
Sun 7-5 0-0 Vekic*
Ashleigh Barty
Three-time Grand Slam champion on BBC TV
Sun almost seems like a veteran out there, like she's played on this court a million times and playing like she's in her back yard.