[Olympics, SF] Federer beats del Potro in a marathon match to reach gold medal round
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