Roger Federer held young pretender Alexander Zverev at bay in a gripping contest on Tuesday (Nov 14) to reach the last four of the ATP Finals and stay on course for a seventh end-of-season crown.
The world number two saw off a spirited challenge from the much-hyped German 7-6 (8/6), 5-7, 6-1 in front of a boisterous pro-Federer crowd to become the first man through to the last four at the O2 Arena.
"It was a good battle and I always enjoy myself at this beautiful arena," said Federer, who has now reached the semi-finals 14 times