Swansea City's Nathan Dyer is to have ankle surgery and will be out for up to two months.
The midfielder has "extra bone growth" in the joint to rectify, leaving the player "bitterly disappointed".
He added: "I started to feel some pain in my ankle after returning from the training camp in America.
"I saw a specialist last week and the MRI scan revealed the extra bone growth at the back of my ankle. There is not a lot I can do about it."
Dyer says he is "determined to work even harder after my operation" to make his mark.
The 28-year-old, who won a Premier League winner's medal during a season's loan at Leicester City, signed a four-year contract extension with the club in August 2016.