Ji, 22, is under contract at the Stadium of Light until 2015 but has fallen out of favour with new manager Gus Poyet and has made only four appearances this season, the last coming back on October 5.

Capped 26 times by his country, Ji joined Sunderland from Chunnam Dragons in 2011 and had a successful loan spell in Germany in the second half of last season with Augsburg, when he scored five times.