Rafael Nadal is into the third round of the US Open after Nicolas Mahut retired through injury.
The number two seed was 6-2 6-2 up before the Frenchman withdrew with an abdominal problem.
"I prefer to be in the third round," said the Spaniard. "I spent a long time on court in the first round. For sure it's not nice to win like this, but that's sport sometimes."
The ten-time Grand Slam won last year's final, defeating Novak Djokovic.
