Hello and welcome to our LIVE coverage of the WTA Championships in Istanbul. First up today we have Serena Williams, who kicked off with a thumping 6-4 6-1 win over Angelique Kerber. This is the Chinese number one's first match of the Championships.

Serena makes it two in a row, with that Na's first match so she still has a chance. Next up we have Azarenka v Kerber. Azarenka's first match of these Champs.

SERENA 7-6 6-3 - GAME SET AND MATCH! Unlike the first set, Serena makes light work of serving out the second - and the match. Some top-class serves there, and one approach shot to bring up 30-0 that she yelps past Na. Three match points brought up as Na puts a backhand drive well beyond the line, and a hold to love and the match as Na goes long again.

SERENA 7-6 5-3 - The first match point is saved as Serena pumps a forehand long. Then a rotten serve about two yards wide allows Serena to dictate the pace of the next rally, but Na readjusts to win the point with a crosscourt forehand. A great point from Na. But Serena takes charge again and has a second match point - which she is unlucky not to take as Na gets the rub of the net. And a lucky Na holds as the net comes into play again. Serena to serve it out.

SERENA 7-6 5-2 - Na is serving to stay in the match but slips behind early on, levelling at 30-30 before being incorrectly called out with her first serve, according to the umpire. Serena should have challenged - it was out! No mind anway as Na double-faults her way to match point...

SERENA 7-6 5-2 - A couple of booming serves put Serena in charge of this game but she goes long as Na manages to get her moving around the baseline. Na has a chance if she can draw out the rallies - and not make mistakes. Which she does again to level at 30-30, Serena is not moving as well as usual and Na must exploit this. And now break point for Na as she deceives Serena with a surprise cross-court backhand. ACE to deuce. Phew. More big serves and Serena holds. Na serving to stay in the match.

SERENA 7-6 4-2 - Na's first ace of the day starts what is a vital game for her. Then she backhands weakly into the net. This has been a poor game by both women's standards. Then another error from Na as she skews one wide under no pressure, 30-30. But Serena returns long and game point Na, which she takes with a vicious cross-court backhand that leaves Serena on her backside.

SERENA 7-6 4-1 - Brilliant from Na as she spins a winner off the baseline to bring back deuce in this epic game - but a rapid first serve down the middle gives Serena another ace. Like buses, you wait all set and three come at once. A blistering second-serve return from Na brings it back to deuce though! And finally Serena holds as she unleashes some power on Na. Saved a break point but should have won that game easily.

SERENA 7-6 3-1 - Serena batters her way to 40-0, her now solid serve doing the trick, but she drops one after a Na return dictates the tempo of the point, before dropping another as she overcooks a drop volley well wide. Poor from Serena. And now deuce as Na's return catches Serena off balance. Finally Serena manages a pair of aces, but they alternate with weak forehands so it's back on deuce. And now break point as Serena goes long... Saved and now advantage as Na spins one long...

SERENA 7-6 3-1 - BREAK! Serena responds that that mini-blow by blistering 40-0 up against serve, but she overcooks her next winner to drop the first break point. Na saves the second of the three with some powerful groundstrokes from deep before blasting a forehand away from Serena, but she double faults away the game with a shocking second serve that almost hits the baseline!!

SERENA 7-6 2-1 - BREAK BACK! Much better from Na as she moves up and down the baseline to leave Serena floundering. Three break points now... The first is saved by a weak Na return off a weak second serve. But Serena then goes long and it's back on serve.

SERENA 7-6 2-0 - BREAK! A double fault from Na sees her slip to deuce. Serena sensing an opportunity here, and it's break point after a horrible error from the Chinese, smashing her volley wide with Serena totally stranded after a weak return. But a wonderful backhand down the line brings back deuce. Flashing return and delicate drop shot from Serena catch Na out, and it's break point no.2! Taken as Na flops one long.

And remember - you can watch this on Eurosport either on TV or on the Player.

Reckon it's straights sets for Serena or will Na show that famous fighting spirit and take it all the way? Is Serena a shoo-in for this or can Maria and Victoria pull off what would be an upset? Have your say @Reda_Eurosport on Twitter.

SERENA 7-6 1-0 - Serena slips 15-30 down on serve but some brutal backhands see her level, responding with a "come on!". This is no walk in the park that's for sure. Na goes long after a spinny forehand and it's game point, but Serena's first serve just kisses the net to her disgust. Would have been an ace. Serena starts the second set with a hold though as Na nets her return.

SERENA 7-6(2) - SET! A dominant performance in that tie-break from Serena as she clicks into gear when it matters. Na did pull one mini-break back with a cool forehand drive angled into the left. But a blistering return from Serena catches Na off guard and it's set points x 4 at 6-2... Taken with a savage return that Na can only spoon wide. Serena still isn't happy and rightly so - she almost blew that. 55 minutes it took in the end.

SERENA 6-6 (4-1) Serena looks perplexed as another weak serve just about clears the net, fortunately for her Na couldn't do anything with it. A mini-break for Serena as her fiery return catches Na on the back foot, the Chinese ultimately netting.

SERENA 6-6 - BREAK BACK! Serena serves for the set a second time. And she completely fluffs her lines again as she fails to move well after her first serves, which are lacking in power and confidence. Now she is three break points down as a flying rally sees Na volley clear. Taken as a dominant baseline rally from Na allows her to send the lumbering Serena staggering into a weak backhand. Tie break it is. What did I say earlier?

SERENA 6-5 - BREAK! Na throws away a point to fall 0-30 down, getting her topspin all wrong on what should have been a winner after Serena's alley-oop just about landed in. And now she's two break points down after a weak, indecisive backhand into the net. She didn't seem to know whether to flick it over the net or pass it down the line. And she completely messes up her crosscourt winner, a yard wide with Serena stranded. Deary me.

SERENA 5-5 - BREAK BACK! Well Na is not going down without a fight as she shows great speed and agility to switch corners on the baseline before passing a wrong-footed Serena to get three break points! And she takes them, breaking back to love as Serena loses concentration!

SERENA 5-4 - BREAK! Williams is on fire right now and blasts a fierce return away. However, her radar is off with a forehand winner that lands a yard or two long. She makes up for that in style to earn two break points, the first saved as she returns long... The second is taken as Na cracks from deep, into the net with her backhand. Four games in a row for Serena now as she serves for the set.