del Potro keeps getting closer to beating Federer.  Federer started the match not playing his usual strategy.  He hit off-pace shots, and shots up the middle.  For a big guy, del Potro moves awfully well.  He hits a great running forehand.  He defends his backhand well.

del Potro took the first set when Federer had a sloppy game, got down double break point.  Fed saved one of the points, but couldn’t save the other, and all of a sudden, Delpo is serving for the first set.

The rest of the match was pretty much a contest of holding serve.  Fed looked sharp on serve, but seemed hard-pressed to deal with del Potro’s power.  He’s never fully in control, but wants to get enough balls back and wait for the del Potro error.

The one thing in Federer’s favor, other than his impeccable serve, was his fitness.  del Potro seemed to labor a bit, and this was evident in the third set.  Federer managed to win the second set in a tiebreak, and escape dangerous break situations in the third.  Federer even broke in the third set at 9-all and was ready to serve out the set when he got broken back at love.

So the match kept going on and on, past the 16-14 he had with  Roddick in 2009.  Finally, del Potro had a shaky game, got down 0-40, but didn’t manage to escape as he had in an earlier game and Federer got up 18-17.  Despite missing practically every first serve and being brought to deuce, Federer managed to hold serve and move himself into the medal round.

This match made history as it became the longest Olympic singles match at 4 and a half hours.  With this win, Federer guarantees he’ll get an Olympic medal.  It will just depend on which color.  This is the one missing piece in the Federer resume.

Up next, Murray takes on Djokovic.