Del Potro wears down Federer to seal semi-final spot
LONDON (AFP) - Argentina's Juan Martin del Potro claimed a crucial 7-6 (7/3), 4-6, 6-3 victory over defending champion Roger Federer on Saturday to book his place in the semi-finals of the ATP Tour Finals.
Del Potro's victory ended Federer's 12-match winning run at the season-ending event and guaranteed he will qualify from Group B along with the Swiss star.
Federer, who has won the Tour Finals title for the last two years, already knew he was through after winning his first two group matches at London's O2 Arena.
The semi-final match-ups will not be decided until after the final group match between David Ferrer and Janko Tipsarevic later on Saturday.