Federer outlasted Canadian Vasek Pospisil 6-3, 6-7 (3-7) 7-5 and will seek his fifth title in his hometown tournament when he faces del Porto on Sunday.
A victory Sunday will also qualify Federer for the field of eight top men's players who will take part in the season-ending ATP World Tour Finals.
Federer will have to first get past del Porto. The top-seeded Argentine dispatched Edouard Roger-Vasselin of France on Saturday 6-4, 4-6, 6-2.
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