Coco Vandeweghe's forehand is a club of a shot that Barney Rubble would be proud of.

A cord-grazing ripper brings up break point at 30-40. Venus Williams wipes that off the board with a body serve.

A tentative prod into the net though gives Vandeweghe another break chance.

Saved.

Double fault though. Venus looking like the semi-final novice as she coughs up a third break chance.

Coco goes long.

On we go.

Venus Williams is in bat first.

Let's go.

Image source, EPA

Coco Vandeweghe's list of victims on the way to the last four is impressive.

World number one Angelique Kerber is the highest profile name, coming a straight-sets cropper in the fourth round.

Wimbledon runners-up Garbine Muguruza and Eugenie Bouchard fell in the quarter-final and third round respectively.

The average rank of her opponents so far in Melbourne? 28. For Williams? 102.

BBC Radio 5 live

Image source, Rex Features

After Rafael Nadal rolled Milos Raonic in straight sets yesterday, the possibility that we might be partying like it is 2008 all over again is very much alive.

Andy Roddick, the only man other than Roger or Rafa to appear at a Wimbledon final for a six year period between 2004 and 2009, has told BBC Radio 5 live that an Australian Open final between Federer and Nadal could be "the most important match in Grand Slam history."

 “The historical context of what we might see, it’s definitely the most important match in Australian Open history if it gets there, possibly in Grand Slam history,” said Roddick.

Federer plays Stan Wawrinka later today at 08:30 GMT before Rafael Nadal takes on Grigor Dimitrov in the other semi-final on Friday.

It is a relatively chilly 20 degrees Celsius in Melbourne. Relative to the highs of the Australian summer, rather than the lows of the British winter that is.

The two players march out on Rod Laver Areana.

Coco Vandeweghe looks so laid-back, she is positively horizontal. All smiles and loose limbs.

Venus Williams is a little more business like, taking her time with some tennis bag admin before joining Coco at the net for the coin toss.

Image source, Getty

The only previous meeting between the two was on the clay of Rome earlier this year where Williams senior progressed 6-4 6-3.

But they are occasional Fed Cup team-mates so they know each other a little better than that record would suggest.

Image source, Getty Images

Image source, EPA

On the other side of the net is a more mellow character.

Venus Williams is the ice to Vandeweghe's fire, the Borg to her McEnroe, the Murtaugh to her Riggs. You know the narrative.

Williams has not featured in a Grand Slam final since Wimbledon 2009. Should she bridge that seven-and-a-half year gap with victory today, it would be the longest gap between Grand Slam final appearances in the Open era.

At 36, she would also be the oldest Australian Open finalist since professionals were allowed into the four biggies in 1968.

Image source, EPA

Coco Vandeweghe is not here to make friends. 

"She does not care what anybody thinks about her, or their opinion," former Wimbledon champion Lindsay Davenport told the New York Times., external

The 25-year-old is a brash bundle of energy and aggression on court and not shy of speaking her mind off it.

Asked about her relationship with her father, she described it as "zero".

“Screw me over once, and you’re not going to screw me over twice," she added.

When fellow American professional Nicole Gibbs tweeted about the possibility of a Hillary Clinton landslide in November's presidential election, she took issue. 

Win or lose today in her first Grand Slam semi-final it will not be for a lack of feist or fight.