Dolgopolov's injury brought an end to the match
Home favourite and top seed Roger Federer made a winning start to his campaign at the Swiss Indoors after his opponent was forced to retire.
Federer was leading Alexandr Dolgopolov 6-4 5-2 when the Ukrainian had to pull out with an ankle injury.
The Swiss will face either Serbian Janko Tipsarevic or Denis Istomin of Uzbekistan in the second round.
Federer lost in last year's final to Novak Djokovic, ending a run of three consecutive titles in Basel.
Dolgopolov fell as he tried to chase down a Federer winner to bring an end to the match after 48 minutes.
Federer got his start in the game as a ball boy in Basel and he now has a 34-7 record at the tournament as he starts the bid for his 65th singles title.
Potenshöjande medel - potenshöjande medel