On-loan defender Sebastian Coates is in talks over a permanent move to Sporting Lisbon, according to reports.
The Sunderland centre-back is currently on an 18-month loan deal but reports in Portugal say the clubs have entered into talks over a possible permanent deal in January.
Coates has impressed officials at the Portugese side this season and they are understood to be keen to make his move a permanent one.
Sporting are reported to have an option to buy the Uruguayan centre-back at the end of the season for £4.5m but reports suggest that may happen sooner.
The 26-year-old joined Sunderland from Liverpool in the summer of 2015 for £2million. He has made 11 appearances and scored three goals so far this season.
It would be a welcome transfer boost for Sunderland, who will need to strengthen their squad in January.
The Black Cats are currently bottom of the Premier League and without a win in nine games ahead of tomorrow's lunchtime kick-off against Arsenal.