France lost key midfielder Patrick Vieira to a hamstring strain midway through the second half but maintained the pressure amid the tiredness as the errorcount rose.
His errorcount was a stark contrast to his performance in his debut season last year, when he was virtually flawless until letting the title slip through his fingers in the final two races.
With Soderling's unforced error-count rising sharply, Federer eased through another service game and, while not needing to find top gear, he was already oozing confidence.