The semi-final match ups have been confirmed at the ATP World Tour tennis finals in London after Swiss star Roger Federer beat Juan Martin Del Potro in the final group match.
Federer staged a superb fightback from a set down to beat the Argentine 4-6, 7-6 (7-2), 7-5 and reach the fiinal four.
The six-time Tour Finals champion qualified in second place in Group B behind the defending champion, Novak Djokovic, and will face world number one Rafael Nadal in the semi-finals at the 02 Arena.
Djokovic will meet Federer's compatriot Stanislas Warinka in the other semi-final.
