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By David Ornstein
1425: Del Potro has only recently recovered from a wrist injury and put in a below-par performance against Murray on Sunday. After dropping the first set, he showed a glimpse of his capabilities in the second but ran out of steam in the third. The 21-year-old US Open champion has the game’s most venomous forehand, as Verdasco is about to discover.1422: A little heads up for later. Murray-Federer will not start before 2045 GMT and you can watch the match on BBC 3, listen on 5 live sports extra and read game-by-game updates here on the BBC Sport website.1418: As the players receive their boxing style introductions to the O2 Arena crowd, this is my chance to ask you to get involved in the chat. You can do so by text to 81111,**606](http://www.bbc.co.uk/dna/606/A59964745)orTwitter**](http://twitter.com/davidornstein)1415: Wherever you are in the world, be sure to tune in to the commentary of the match on BBC Radio 5 live sports extra, which you can access through this website. Why not listen and read at the same time.1412: Remarkably for two players within the world’s top 10, Del Potro and Verdasco have never previously met on the ATP Tour. Their only career meeting, in a challenger event on the Segovia hard courts in 2006, saw Argentina’s Del Potro come from a set down to win in three.1410: Both Del Potro and Verdasco made losing starts to their Group A campaigns on Monday, going down to Murray and Federer respectively. The loser might as well book his flight home. That’s how big this one is.1405: It’s the one you’ve all been waiting for. And it gets under way in about nine hours time. So while you’re waiting for what promises to be an absolute belter between Andy Murray and Roger Federer, how do you like the sound of Juan Martin del Potro against Fernando Verdasco