Roger Federer will open his title defence on Monday at the Swiss Indoors against German qualifier Benjamin Becker after French opponent Jeremy Chardy withdrew injured before the start.
Chardy was reported to be suffering with neck pain as he handed over his spot in the draw.
He is the second injury withdrawal after world number four Andy Murray, who is not playing the ATP season's penultimate tour event due to a back injury.
Federer has won five of the last six editions at his hometown event and will open play on Monday evening.
The Swiss world number one stands 2-0 over Becker without the loss of a set.