Six-time champion Roger Federer rallied past Juan Martin del Potro 4-6, 7-6 (2), 7-5 to reach the semifinals of the ATP World Tour Finals for an 11th time on Saturday.

Federer will next face Rafael Nadal while Novak Djokovic will take on debutant Stanislas Wawrinka in the other semifinal at the year-end tournament.

Both Federer and del Potro needed a win in their final round robin match to progress from Group B.

Only once in 12 appearances has Federer failed to advance to the last four.

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