Hello and welcome to LIVE coverage from the second of the women's semi-finals. We've had the all-Russian semi-final where Maria Sharapova beat Ekaterina Makarova. Now it's time for the all-American semi-final between world number one Serena Williams taking on unseeded rising star Madison Keys.

So it will be world number one Serena Williams against world number two Maria Sharapova in the final on Saturday. Williams clearly has a huge amount of respective for Keys as she gives the youngster a warm hug at the net before standing and applauding Keys off the court along with the crowd. That win, by the way, also ensured Sharapova cannot overtake her as world number one this week, no matter what happens on Saturday night.

Williams 7-6(5) 6-2 Keys. Game, set and match. This time Williams does seal the win, finally finding the winner - a second serve ace. Williams is through to her sixth Australian Open final and remains unbeaten in semi-finals in Melbourne but not without a real fight against a very exciting player for the future. What a fantastic match from Madison Keys.

Williams 7-6(5) 5-2 Keys. Ad-40. The crowd are absolutely loving the gutsy effort by Keys as she works her way into the net and finds a backhand volley winner to take the first point of the game. Williams bounces back and even moves ahead with an ace but a 69mph second serve from the world number one is duly punished by Keys to draw level at 30-all. Williams has another match point, this time on her own serve however, when a running Keys goes wide with a backhand across court. Again, though, Keys saves it - nearly knocking Serena off her feet with the power of her backhand reply. Williams goes well wide with an completely off-balance backhand, stumbling back as she plays the ball. Keys goes just long with a backhand return down the centre of the court to hand Williams a ninth match point...

Williams 7-6(5) 5-2 Keys. Williams applauds, along with the crowd, a brutally flat running forehand winner down the line from Keys to bring up a game point but there's a squeal of frustration from the 19-year-old as she goes long with a mis-timed forehand down the centre of the court that almost hits Williams on its way through. The world number one gets a sixth chance after an agonising miss on a smash. But again Keys saves it with a great serve that Williams can only return long before earning herself another game point with a huge serve. She nets a forehand to gift Williams a seventh match point. But Keys saves this one with a smash that draws the low netted backhand from Williams before going on to hold with a forehand winner down the line and a big second serve that Williams can only return long. Sensational defence from Keys and Williams will have to serve it out!

Williams 7-6(5) 5-1 Keys. Deuce. Keys is twice pegged back by Williams, just going for a little too much an unable to find the court. A forehand winner after maneouvring Keys out of position then brings up a first match point for the world number one. Keys saves it with an ace! Fantastic resistance once again from the 19-year-old. A vicious backhand return of serve winner earns Williams a second but again Keys saves it with a huge backhand down the line followed by wrong-footing backhand winner. The 19-year-old nets an inside out forehand approach shot to hand Williams a third but still Keys won't go away and she produces yet another ace to save it. A fourth match point is saved after some great defence from Keys, pushing Williams wider and wide until she nets an off-balance forehand. And an inside out forehand winner across court from Keys, off a shorter ball, saves a fifth. Spectactular stuff from both players.

Williams 7-6(5) 5-1 Keys. A huge serve out wide followed by a forehand winner down the line. Ace. Unreturnable serve. Ace. Ace. It's a love service game for Williams that leaves her just one game away from the final. Keys will have to serve to keep this match alive.

Williams 7-6(5) 4-1 Keys. Break. Great length from Williams as she lands a forehand right on the baseline on her way to bringing up another two break points. Keys saves the first with an ace right into the corner and the second with a kicking serve that Williams simply cannot deal with. But a dipping backhand from the world number one draws the backhand volley just wide from Keys, Williams racing up the court and finding a forehand pick up winner off the drop shot just in case. And this time, there's nothing Keys can do to save the break point, conceding her serve for a second time in this set on a double fault. The youngster just running out of resistance now and Williams leads by a set and a double break.

Williams 7-6(5) 3-1 Keys. Keys sneaks ahead on the Williams' serve once more as the world number one completely mis-times a cross court forehand and sends the ball sailing long. An ill-advised choice of shot, though, costs the 19-year-old as she goes for the backhand down the line too early, sending the ball wide instead and Williams goes on to hold without dropping another point - the serve again doing most of the work.

Williams 7-6(5) 2-1 Keys. Yes, Madison Keys! At 19 years old she is simply refusing to be scared off by the situation and she races through a love service game to get her side of the scoreboard ticking over once more, including a huge bit of defensive running to bring up game point. Williams smiles wryly after losing that point with a netted forehand and then even more so when heading back to the chair as another huge first serve from Keys can only be returned into the net by Williams.

Williams 7-6(5) 2-0 Keys. Keys finds the line on three successive ground-stokes to get off the mark before drawing consecutive errors from Williams, one off either side, to earn the 19-year-old two immediate break back points. Williams saves the first with yet another ace while Keys squanders the second with a backhand just long across court. And from there Williams goes on to hold to consolidate the break with another ace and big second serve that Keys can only net.

Williams 7-6(5) 1-0 Keys. Break. Keys opens the second set comfortably enough before netting a forehand down the line to gift Williams a first point. A cross court forehand wide off the shorter ball before a forehand long down the line off another short return hands Williams a break point. And, ouch. A fourth successive forehand error, again long down the line, hands Williams the early break in this second set. Is that the turning point for Williams?

Williams 7-6(5) Keys. Set. And there is the first set to Williams, the world number one coming up with another stunning serve (down the centre of the court) that a lunging Keys can only return long off the forehand wing. A serving masterclass from both women so far today but it is Williams who sneaks the first set.

Williams 6-6 (6-3) Keys. Tie-break. Williams goes long with a forehand, confirmed by a hawkeye challenge, to gift Keys another point but consecutive netted forehands from the 19-year-old hand Serena three set points. Keys saves the first two with aces down the centre of the court but the third set point is on the Williams serve.

Williams 6-6 (4-2) Keys. Tie-break. Williams opens the breaker with an ace before Keys responds with a huge serve of her own. The world number one does get the mini-break on the third point though with a ferocious return that Keys can only net off the forehand wing. Another big serve followed by an ace out wide once again extends Williams' lead. Keys halts Williams' march through the breaker just before the change of ends with an inside out forehand that Serena can only send back into the net.

Williams 6-6 Keys. It will be a tie-break to decide this set as Keys looks to be cruising to a easy service hold only to be pegged back a little after a couple of errors. Keys also got a little lucky early in the game when her forehand caught the top of the tape but she hits the ball with such ridiculous power that it bounced over for the perfect drop shot. There's nothing lucky about game point though as Keys holds with an ace.

Williams 6-5 Keys. Nifty footwork from Keys as she lies in wait for the serve out wide before finding the inside out forehand winner across court off the shorter ball. Williams levels up before a thumping return from Keys catches her unawares for the 19-year-old to sneak ahead once more. The perfect backhand lob from Williams has her level at 30-all before an ace brings up game point. Keys denies her though with a backhand winner down the line that wrong foots Williams and she is so close to earning another break point when her forehand catches the top of the tape and just decides to fall back on to her side of the net. It's game point Williams instead and this time she takes it when Keys goes wide with a low, inside out forehand volley across court. Keys will have to serve to stay in this opening set for a second time. Can she hold to force the tie-break?

Williams 5-5 Keys. Williams exploits the leg injury with a cross court backhand that Keys is a little slow to move to, netting her backhand as a result. But the 19-year-old still has a second game point and she finds a fourth ace to seal the game that sees her level up once more.

Williams 5-4 Keys. A netted forehand from Williams is the only blip in the game for the world number one as she reaches five games first, testing Keys on her ability to serve to keep this opening set alive.

Williams 4-4 Keys. Super resistance from Keys as she holds for the loss of just the one point. The little tweak of her injury in the previous game just seemed to rattle her a little but she easily makes it up to a net cord from Williams and puts the forehand away down the line for a winner to get her side of the scoreboard ticking over once more.

Williams 4-3 Keys. A love service game from Williams to get her out in front for the first time in the match. The world number one is definately starting to move better and finds another slider out wide for an ace before sealing the game with a big serve that Keys can only return long off the backhand wing. Huge game coming up for the 19-year-old after the change of ends as she looks to arrest Serena's momentum.