It wasn't televized for obvious reasons but I linked the article.
Here's another one
How to... beat both Williams sisters in one afternoon | Sport | The Observer
Karsten Braasch is the German tennis player who did just that in 1998
Sunday 2 September 2001
Observer Sport Monthly
It was the 1998 Australian Open and the Williams sisters, Venus and Serena, had seen some of the male players practising. On the basis of what they saw, they were convinced that they could beat a man ranked around 200 in the world and wanted to set up a game. At the time I was ranked 203 so the men's tour manager mentioned the possibility of a challenge to me, thinking that I was the perfect candidate. I didn't take much persuading, it seemed like a fun thing to do.
My advice if you're ever in a position to play a match of this nature is be patient - don't be annoyed or surprised if your match against the Williams sisters is cancelled, as they both have very busy schedules. My game against them had to be re-organised at least a couple of times.
Preparation is crucial. Remember that a game like this is light-hearted - taking it too seriously would be a mistake. My training regime consisted of a leisurely round of golf in the morning followed by a couple of shandies. I turned up on court feeling suitably laid-back.
My first game of the afternoon, just a one-set match, was against Serena. A hint: try and play your match somewhere quiet, where you're not going to be pestered by big crowds or lots of press - we were out on one of the back courts at Melbourne Park, No 17 I think it was. I felt so relaxed that I didn't even warm up properly. We started playing and I raced into a 5-0 lead.
At this point Venus turned up to watch. She had just finished a press conference after a quarter-final loss against Lindsey Davenport. In the end I won my game against Serena 6-1 but by the time we were at the net shaking hands, Venus was on court, ready to have a go against me as well. The game against Venus was very similar. I ended up winning 6-2.
Both sisters are great tennis players and hit the ball extremely well. However, if you've been playing on the men's tour there are certain shots you can play that are going to put them in difficulty. Try and put a lot spin on the ball - I was hitting the ball with a degree of spin they don't face week-in, week-out. Another key is to chase down every shot. In our match, they were putting shots into the corners that on the women's tour would be winners but I was able to return them.
In the end I won, but neither myself, nor Venus or Serena took the game too seriously - we were just having a bit of fun.
Apparently, after the game, Serena and Venus immediately told the press they wanted to challenge a male player again. This time they revised the ranking of the man they wanted to face, to 350 in the world. I informed the journalist who told me this that in the next week I was set to lose a lot of ATP points and drop down to 350 in the rankings. I told him that if Venus and Serena waited just one week they could challenge me all over again!
That never came about, but when I saw Venus a few months later at the French Open she came up to me with a big smile on her face and said, 'You know that thing in Australia - it never happened!'