Roddick, tracking down a shot behind the baseline as he did so often. Photo via AP

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Men's Fourth Round:

Andy Roddick (USA)[7] def. Fernando Gonzalez (CHI)[11] 6-3, 3-6, 4-6, 7-5, 6-2 -- This was a seriously gutsy effort from Roddick, in which he showed some phenomenal spine, if not always stellar brain.  Roddick got stuck in baseline rallies far too often with the harder-hitting Gonzalez, and didn't seem to do as much chipping-and-charging or serve-and-volleying as you would expect in a match he won.  But he found away, squandering multitudes of break points in the fourth before finally getting the set on a vaguely controversial ruling by Enric Molina in which he deemed that Gonzalez was going to let a ball pass him.  The fifth was a walk in the park, and it was sort of a shame that it ended on a Gonzalez double fault that prohibited an especially exuberant Roddick celebration.  The big question going forward for Roddick is how his knee will hold up tomorrow and then Tuesday against Cilic.

Marin Cilic (CRO)[14] def. Juan Martin del Potro (ARG)[4] 5-7, 6-4, 7-5, 5-7, 6-3 -- I actually thought this match was going to be a much more lopsided victory for Cilic, based on how battered del Potro had looked in his earlier matches.  But del Potro, once known as one of the most questionable players on either tour in terms of injury retirements, has completely transformed into a total hoss when it comes to toughing out injuries.  It looked like del Potro would escape after Cilic choked away the fourth, but the Croat came out playing absolutely perfect tennis early in the fifth to blitz his way to a 4-1 lead that he hung onto for the win.  If del Potro takes the needed time to rest and rehab, he should be back in top form by Dubai or so.

Andy Murray (GBR)[5] def. John Isner (USA)[33] 7-6(4), 6-3, 6-2 -- Like a lot of battles with big disparities in experience (though not really ability), this one was over at the end of the first set.  After making no noise on return through Murray's first five service games, Isner turned up the pressure big time with Murray serving at 5-6, and got himself a set point.  But he got too fancy, and nobody out-fancies Murray with any success.  The lesson Isner needs to take away from this loss, in my mind, is that it's OK to be fairly one dimensional when that dimension is as awesome as his is.  Smarter approach shots also are needed.  But Murray looked solid, and on form he looks to be a good bet to take out the defending champ in the quarterfinals.

Rafael Nadal (ESP)[2] def. Ivo Karlovic (CRO) 6-4, 4-6, 6-4, 6-4 -- Nadal really has not looked at his sharpest so far in this tournament, but he didn't really either in the early rounds of the 2009 Aussie, so who knows.  He wasn't going to appear his sharpest against Karlovic, no matter how his form was previously.  Karlovic played pretty decently, but Nadal did what he had to do to get a win.  The big surprise here: not a single tiebreak set.