It's been recently revealed that SNSD's Tiffany injured her right ankle during SM Town's concert that was held in Seoul on August 21st. She is currently wearing a cast, and according to SM Entertainment, her injury fortunately is not serious. Through a phone call with Newsen, a representative of SME stated:

To protect her ankle, she had to wear a cast. She injured her ankle during SNSD's performance during the concert. Due to the upcoming Japanese showcase, we thought it was the best choice to make her wear a cast. ... Her injury will not affect SNSD's upcoming showcase. ... The girls on the 23rd left to Japan to prepare for their Japanese promotional activities.

The girls of SNSD, who are making their Japanese debut with their single Genie on September 8th, will have a showcase in Tokyo, Japan's Ariake Colosseum on the upcoming 25th. Someone was able to take a photo of Tiffany at the airport, and here is a fancam that caught the scene of Tiffany's injury. Best of luck to Tiffany, and let's hope that she has a speedy recovery! Thanks to banana_concept for the tip.