By Graeme Bailey Follow on Twitter
Coates spent last season on loan at Sunderland having failed to establish himself as a first team regular at Anfield since moving to Merseyside in 2011.
And Goal understands Sunderland boss Dick Advocaat has given the move to sign the Uruguayan on a permanent deal the green light.
Liverpool are understood to want £4 million for the 23-year-old, with Sunderland hopeful of completing a deal closer to £3m, but the transfer is expected to be concluded this week.
With Coates set to leave the club, Liverpool have made an enquiry for Charlton defender Gomez.
Liverpool are believed to be in pole position to sign the 18-year-old, who is being monitored by as many as six Premier League clubs having made his breakthrough at Charlton last season.
Middlesbrough defender Gibson, who is part of the England Under-21 squad for the European Championships, has also attracted interest from Liverpool.
Manchester City and Everton are also understood to be keen on the defender, with Middlesbrough hoping to fend off potential buyers by placing a £10m valuation on the 22-year-old.