Two big serves from Jannik Sinner and there's not much Tristan Schoolkate can do about those.

But the Australian comes out the better of the two during a quick exchange at the net, and again with a lobbed return.

Two aces get the job done for Sinner, though.

Veronika Kudermetova lets out a roar as Katie Boulter can't get anything meaningful on her powerful serve.

A set which swung one way and then another and Boulter will be disappointed that she put in all the hard work to stay in the set then couldn't get it over the line.

Fair play to Kudermetova to recover from that and win the tie-break.

Veronika Kudermetova goes long from a good Katie Boulter serve but does well to stay in the rally and fires down the line out of Boulter's reach.

Three set points.

Good serve from Katie Boulter and Veronika Kudermetova can only push into the net.

But the world number 75 looks in control of this tie-break as Boulter does well to get the pick up but can only float it the wrong side of the net.

Tristan Schoolkate moves forward and crouches low to lift over a backhand drop shot and it catches Jannik Sinner completely unaware.

The crowd are liking this showing so far from their Australian wildcard.

Leon Smith
GB Davis Cup captain on BBC Radio 5 Live and BBC Sounds

An impressive three points there from Veronika Kudermetova especially on the serve. When she finds her first serve it's a really big weapon, she's not the tallest player out there but she's got a really fast arm and she's got good speeds.

Katie Boulter has put in a lot of hard work to get back into this set. It's a miracle we're in a tie-break really.

But she's struggling here as Veronika Kudermetova takes the first three points.

Tristan Schoolkate isn't making this easy for Jannik Sinner in these opening stages and he forces the Italian to deuce here.

But the world number one wriggles free with an ace before Schoolkate sends a backhand wide.

Veronika Kudermetova does her bit and we're off to a tie-break.

Katie Boulter to serve first.

Leon Smith
GB Davis Cup captain on BBC Radio 5 Live and BBC Sounds

This is really impressive from Katie Boulter, she's just managed the situation so well, she's stayed calm and she knows what she's capable of.

Katie Boulter is on an absolute roll.

She takes the hold to love and will have the chance to break Veronika Kudermetova to take the set.

So far so good for Tristan Schoolkate. Two service games, two holds.

Not bad against the world number one and defending champion.

Brazilian teenager Joao Fonseca did so well to take the opening set, but he's facing an uphill battle now.

The 18-year-old qualifier lost five games on the bounce as Italy's Lorenzo Sonego sped his way through the third set to take a 2-1 lead.

Katie Boulter back in business!

That's four games in a row from the British number one and what a recovery it is from being 5-1 down.

Veronika Kudermetova loops wide and we're all square in set one.

It looked like a back or potentially rib issue for Veronika Kudermetova as she was lay on her front receiving treatment from the trainer.

Whatever it is looks to have hampered the Russian somewhat and Katie Boulter works herself a break point to level things at 5-5.

Jonathan Jurejko
BBC Sport in Melbourne

If you’ve not heard of Joao Fonseca yet, you soon will.

The ball-bashing brilliant Brazilian is the new breakout star in the men’s game - and Melbourne Park knows it.

Scores of fans are queuing outside the 1573 Arena where the teenager faces Italy’s Lorenzo Sonego.

Not an empty seat left and barely anyone willing to budge.

Image source, BBC Sport

Image source, BBC Sport

That's exactly the kind of start you would expect from Jannik Sinner as he races to a 40-0 lead.

But, wait! The world number one nets on the next point and then double faults. Tristan Schoolkate can't make the most of the Italian's blip, though, and finds the net to hand over the hold.

We're back under way after that medical time-out for Veronika Kudermetova.

The Russian is serving for the opening set.

Not the best of starts for the Australian wildcard. Some nerves perhaps for Tristian Schoolkate as he concedes the first point with a double fault.

But he battles his way through and gets on the board. That will help with the confidence levels.

Veronika Kudermetova is now receiving a medical time-out.

Katie Boulder is just trying to keep warm by hitting some balls from the back of the court.