Sunderland will send winger Charis Mavrias back to Greek side Panathinaikos, according to reports.
The Greek international was signed by Paolo Di Canio 18 months ago, but he has rarely featured under current boss Gus Poyet, with his last appearance coming a year ago.
The Daily Star claims that Celtic have been tracking the 20-year-old, but Panathinaikos hope to seal a loan deal until the end of the season before Monday's transfer deadline.
Sunderland paid Panathinaikos £2.5m to sign Mavrias.