BASEL, Switzerland -- Roger Federer easily won his opening match in his hometown tournament, beating Alexandr Dolgopolov 6-4, 5-2 in the Swiss Indoors.
Federer was serving for the match Monday when his Ukrainian opponent fell and hurt his ankle. Two trainers tended to Dolgopolov but he was unable to continue, ending the match in 48 minutes.
The top-seeded Federer will meet Janko Tipsarevic or Denis Istomin in the second round.
Federer won this tournament for three straight years before losing to Novak Djokovic in last year's final. Djokovic begins his title defense against Ernests Gulbis.
John Isner rallied from a set down to defeat Frenchman Michael Llodra 4-6, 7-5, 6-3. The eighth-seeded Isner hit 20 aces in the win.
Also Monday, qualifier Robin Haase beat Swiss wild card Stephane Bohli 6-4, 6-3.