Jack Sock claimed the Delray Beach trophy on Sunday after Milos Raonic was forced to withdraw with muscle damage.
Sock won his third ATP Tour title without a ball being hit in anger in the final as Raonic withdrew before the players started warming up.
Raonic said he felt a sharp pain early in the second set of his semi-final match against Juan Martin del Potro while chasing down a drop shot.
Although he expected to play Sunday’s final, his injury got worse overnight and he was left with little option but to pull-out.
“I thought it might just be wear and tear, but I woke up this morning not really able to walk,” said Raonic.
“We did about two hours of therapy this morning trying to calm it down and saw it wasn’t making much progress, so we came to the conclusion it was a hamstring strain.
“It’s disappointing in a lot of ways.
“I’ve been unfortunate with injuries and have been doing everything I can to prevent them. It’s been three tournaments in a row where I’ve sustained some sort of muscle damage. And it’s disappointing for the sole fact that you’re one match away from a title. It’s not easy to accept.”
On the contrary, Sock admitted he was delighted to lift his second trophy of 2017, even if it was under dubious circumstances.
Sock didn’t drop a set in claiming victory this week. He improves to 11-1 this season and will move to a career-high number 18 in the Emirates ATP Rankings on Monday.
However, the prodigy has his eye on cracking the Top 10 and beyond.
“I’m playing these tournaments every week to try and win,” Sock said.
“Tennis-wise, physically and mentally, I think I’m ready to make that jump and my tennis is speaking for itself.
“I need to just keep doing all of the right things to keep moving forward.”