The first two matches have been played in the O2 Arena in London. Andy Murray firstly defeated struggling Del Potro 6-3, 3-6, 6-2 before Roger Federer launched a great comeback to down Fernando Verdasco 4-6, 7-5, 6-0.
World number one Roger Federer was looking in trouble when he was a set down and a game away from a tiebreak, but he decisively broke Verdasco in the 12th game of the 2nd and then walked through the decider 6-0. Looking as though he is possibly running out of steam at the end of the season, this should sound a warning to his rivals that he's not finished yet and can still turn out a love set when he's in the mood.
Meanwhile, Andy 'can't-win-a-major' Murray never will. Reflecting on last year's semi-final defeat to Davydenko, he maintained he had no regrets about going all out to beat Roger Federer in a dead rubber for him in the final group stage match. He was too tired the next day and as a result, lost. But he's well used to that now isn't he?
"I'd do the same thing again," he remarked, about doing everything to beat Federer in a pointless match at the expense of winning the competition. Stupidity.
"Unfortunately it didn't go well for me the next day but winning against Federer six times and losing three times, I can keep that with me for my career," said the unkempt Scot. Just for the record, Andy-dipstick-Murray, head-to-head records count for nothing and are pretty useless statistics in determining greatness. Can you name the head-to-head record between Borg and McEnroe? How about Sampras and Agassi? No. The only thing that matters is Grand Slam titles.
And Murray finishes it off with the most ridiculous quote I've ever heard. Ok, brace yourself, here it comes: "It's not always just about winning tournaments all the time, sometimes it's nice to beat the big players in epic matches and unfortunately sometimes that takes it out of you a little bit."
Sorry to be the one to break it to you Andy, but actually it IS about winning tournaments all the time, in particular, Grand Slam tournaments. It will come as no surprise that Murray's victories over Federer have come in small competitions that are pretty meaningless to a multiple Grand Slam champion, but absolutely vital to players who don't have a prayer in bigger events. Most notably, Federer gave Murray a good trashing in the US Open final of 2008. The final score read 6-2, 7-5, 6-2 on that occasion.
And maybe, just maybe, he has finally realised he is not future champion material in admitting that 'it's nice to beat the big players.'
It will be an interesting match between these two players from opposite ends of the tennis greatness spectrum. I wouldn't be surprised if Murray won. But we all know that Federer is a winning machine. He selects the events that are most important - Australian Open, Roland Garros, Wimbledon, Flushing Meadows - and is always meticulously prepared to win when it matters.
And that's the difference between Federer and Murray. That's what makes one a memorable champion and the other a forgotten also-ran - the Scot wins when the stakes are low. Federer wins when it really matters.