Jeff Tarango
Former professional tennis player on BBC Radio 5 live sports extra

Nadal's serve is so deceptive because he throws in so much spin and speed. Those lefties can get you!

Rafael Nadal gets the hold. Just cranking through the gears there, the Spaniard.

He's angered the matador...

Rafael Nadal grunts into a hammer of a forehand that sends Chung the wrong way.

40-15.

Wicked forehand from Chung Hyeon that Rafael Nadal can only plod into the net. 0-15, and he's looking more confident in this second set.

That was a leaping, two-feet-off-the-ground backhand from the South Korean, and it gets Rafael Nadal scampering across the baseline - he's giving the Spaniard shuttles at the minute, evoking memories of hellish pre-season training camps. And a solid hold for the 23-year-old.

Right Chung Hyeon, whatcha got in this second set? Didn't do too much wrong in the opener, the world number 170... the guy at the other end is just a bit good.

*denotes next server.

Jeff Tarango
Former professional tennis player on BBC Radio 5 live sports extra

It's a good match. Chung is just failing on a few opportunities he is not expecting. Nadal is giving a lot of average shots and is making unforced errors - things you don't usually see. But Chung is not capitalising on them. A top-10 player would be beating Nadal right now.

No mistake with the second from Rafa. A thundering ace. He takes the opening set.

Good hustle from Chung Hyeon as he keeps Rafael Nadal working, the ball comes back with interest but eventually the Spaniard miscues.

First set point saved, one to go...

Deft from Rafael Nadal, a subtle drop volley and that's two set points.

Britain's Dan Evans and Cameron Norrie are back in action in the men's doubles and they are up against the top seeds from Columbia - Juan Sebastian Cabal and Robert Farah.

So far, it's even stevens.

Chance!

But Chung Hyeon can't take it.

Rafael Nadal's overhead at the net was untidy and the South Korean can only pat his passing effort into the net.

15-15.

Right, Rafa to serve for the first set now...

The world number two flicks a couple of loose hairs behind his ear and then steams down a serve, but Chung is equal to it and gets the Spaniard on the run.

Rafa goes screeching across the tarmac and can't wind his backhand on target. 0-15.

Image source, Reuters

Jeff Tarango
Former professional tennis player on BBC Radio 5 live sports extra

That is something you won't see very often - Nadal making unforced errors. He's not been playing great. He will be looking at his box and saying 'what's going on, something isn't quite on'.

Rafa's vest is now drenched in sweat as he mimics a shot that just went wayward. It doesn't help the Spaniard, who whacks the next effort into the tape as Chung holds.

Chung Hyeon serving to stay in the opening set, after patiently waiting for some spectators to find their seats.

Wonderful backhand from the 23-year-old as he flicks it into the space vacated by Rafael Nadal to edge into a 30-0 lead.

Mini scare over for Rafael Nadal. He quickly turns this game around with a crunching ace and another wrist-wrecking serve to hold.

*denotes next server.

Cracking tennis, this.

Chung takes the point to Nadal but leaves a pick-up forehand at the net hanging and the Spaniard storms forward to swat it away with a whipping winner.

15-30.

Oooh. Chance to break back immediately? The South Korean engineers a mini-break as Rafael Nadal slaps one into the net tape.

Classy shot from Chung, drifting towards the tape and skidding down a volleyed winner from height on his backhand side. 0-15.

*denotes next server.