The result was totally unexpected since six-times Wimbledon champion Federer had not lost a match at Halle since 2002, winning the title five times, and had beaten Hewitt in their last 15 showdowns.
Hewitt, a former Wimbledon champion himself, ended the two hour 20 minute contest when his forehand hit the net tape and dropped dead on Federer's side.
Before Sunday, Federer had been defeated on grass just once since 2003, that coming in the 2008 Wimbledon final against Rafael Nadal.