Novak Djokovic was forced to fight hard for a three-set victory over Xavier Malisse at the Swiss Indoors in Basel.
The world number one limped past the Belgian 6-2 4-6 7-5 in over two hours on his first return to action since his US Open victory in September.
Djokovic has been suffering from a recurring back injury since his epic victory over Spaniard Rafael Nadal at Flushing Meadows earlier this year.
"I'm only just back from the biggest injury of my career. It was a big ask for me to have played really well," said Djovokic.
"I had too many errors and too many double faults. But I'm happy just to be playing tennis again."
The victory takes the Serbian's record for the season to 65-3, while he can also boast three Grand Slam titles this year after successes at Wimbledon and the Australian and US Opens.
