Serena Williams (USA) bt. Venus Williams (USA) 6-4, 6-3
Novak Djokovic (RS) vs. Kevin Anderson (ZA) 6-7(6), 6-7(6), 6-1, 6-4 – play suspended, bad light

There was a moment during the first set of Novak Djokovic’s yet-to-be-completed fourth round match with South Africa’s giant Kevin Anderson when Peter Fleming, commentating for the BBC, said “I can guarantee you that Novak isn’t having fun out there”. If this is true then you have to start to wonder why the hell any of us are bothering.

Enjoying it or not, should Djokovic complete his fightback this afternoon, his half of the draw is still filled with potential pitfalls. His nemesis from Roland Garros, Stan Wawrinka, is aiming to renew their acquaintance in a semi-final which would represent the Swiss’s best ever run at SW19. To do so, Wawrinka must first beat Richard Gasquet, who finally downed the flamboyant Nick Kyrgios. Gasquet is playing magnificently and, although I do not believe he is a contender to win the title, he is showing all the signs of a player with the potential to knock out someone who might have been. In the other half of the men’s tournament, the magnetic pull of a Murray vs. Federer semi final still seems pretty inescapable. Should it come to pass, it promises to be quite a match.

Even to look at it from its most base aspect – prize money (something, incidentally, that Fleming’s BBC colleague Andrew Castle is particularly keen to focus on) – Novak Djokovic wasn’t having a particularly bad day in the grand scheme of things. When the game restarts on Court 1 at lunchtime, the player who doesn’t make it through to the Wednesday’s quarter finals will soon have a cheque for £127,000 plop through their letterbox. That’s not bad for a few hours work. You might, indeed, consider it to be something of a spicy meatball. And you’d be right. Hell, Novak, if you are really not having fun out there, I would happily take your place. Lose a tennis match! £31,750 an hour. Plus all the lemon barley water you can drink.

In case anyone ever wonders what became of the great ideological battle that raged throughout the 20th Century, capitalism won. It takes a truly dominant system to see an activity designed as a hobby, a pastime, and to commoditise it into an aspirational, year-round lifestyle choice. Indeed, out of the seventeen players still active in the Singles draw, eight are from former Eastern Bloc countries, either directly or through a parent. Karl Marx and Friedrich Engels, your boys took a hell of a beating.

But wait a moment. Tennis as a sport emerged from the Royal Courts of 13th Century France. It has always been a game of the wealthy and privileged, the upper class. The bourgeoisie. So perhaps the fact that it has now been exploited to make the fortunes of countless people who would otherwise be forced to eke out an existence in developing countries means that it is, in fact, the greatest ever victory for Communism? It’s hard to know for sure without consulting Dennis Skinner, and he isn’t answering my calls. Not after the last time.

One man whose lifestyle has definitely been taken up a notch by tennis is Richard Williams, the father of Venus and Serena. Before either was born, he had watched Virginia Ruzici (incidentally, a Romanian from the Ceausescu-era) raking it in hand over fist. Discovering how much tennis professionals could make, he decided that his daughters could make him a bloody fortune. It’s perhaps one of the most remarkable stories in the history of professional sport, when you think about it: Williams’ plan first called for him to have the required daughters, before training them up for success. For many people, the first thing can prove elusive. For Williams, the second should have proved fairly insurmountable – he had absolutely no experience as a tennis player or coach. Yet, 35 years on and here we are.

In fact, there they both were. Venus and Serena met on Centre Court yesterday, the world rankings and seeding responsible for the fact that the two most pre-eminent female grass court players of their era were meeting in only the fourth round at Wimbledon. Since 2000, the Williams sisters have won ten of the 15 Ladies Singles titles. On four occasions, the final was between just them.

But therein lies another truth: matches between the sisters have rarely if ever been classics. Of those four finals, only one went to a third set: Serena’s second title in 2003. For some, the whole thing is downright fishy, with rumours of collusion within the Williams camp refusing to desist. This is one of the many reasons why finding two siblings at the top of the same activity is rare. Having been competing with your brother or sister throughout your childhood, most people prefer to plough their own furrow rather than submitting their intra-family tussle to a wider, more objective, scrutiny.

In the case of the Williams sisters, it is Venus who bears the burden of not even being the best at tennis in your own family, although her 2011 diagnosis of the autoimmune disorder Sjogren’s Syndrome offers a reasonable justification. Yesterday’s match was rather less anticipated than the previous meetings at the All England Club, with Serena considered a heavy favourite. This knowledge did not seem to weigh too heavily on her and she won the first eight points of the match to take an immediate 2-0 lead. Never really troubled, Serena’s march towards history seems to be back on track after the trauma of Heather Watson’s fightback last Friday. With the other half of the draw opening up, only a potential semi-final meeting with Maria Sharapova -finding form at Wimbledon for the first time in four years – looks capable of stopping her. Like a man with a carrier bag, stepping in front of a tank.

All the fourth round matches were played yesterday, so here is the quarter final draw in full (and their brackets):

GENTLEMEN’S SINGLES (matches scheduled to be played Wednesday)

Novak Djokovic (RS) [1] or Kevin Anderson (ZA) [14] v. Marin Cilic (HRV)
Stanislas Wawrinka (CH) [4] v. Richard Gasquet (F) [21]

Andy Murray (GB) [3] v. Vacek Pospisil (CDN)
Roger Federer (CH) [2] v. Gilles Simon (F) [12]

LADIES’ SINGLES (matches scheduled to be played today)

Serena Williams (USA) [1] v. Victoria Azarenka (BL) [23]
Maria Sharapova (RU) [4] v. Coco Vanderweghe (USA)

Garbine Muguruza (E) [20] v. Timara Bacsinszky (CH) [15]
Madison Keys (USA) [21] v. Agnieszka Radwanska (PL) [13]