Uruguay international Coates had struggled to earn playing time at Anfield and Sunderland boss Gus Poyet snapped up his compatriot before the transfer window closed until January.

The 23-year-old -- who sprang to prominence in the Uruguay side that won the 2011 Copa America -- made only 24 appearances, with just six starts in the Premier League, during his three years with Liverpool.

"Defender Sebastian Coates has joined Sunderland on a season-long loan from Liverpool," a Sunderland statement confirmed.

"The 23-year-old Uruguay international is the Black Cats' eighth summer signing."

Coates signed for Liverpool in 2011 from Nacional and returned to his former club on loan last season.

Poyet also completed his loan move for Argentina international Alvarez, who has scored 14 goals in 90 appearances for Inter.

"I'm very happy to be here. It's a great opportunity, a great club and I'm looking forward to playing in England and playing my part for Sunderland," Alvarez said.

Alvarez has seven caps for Argentina and was part of the World Cup squad in Brazil earlier this year that reached the final only to lose to Germany 1-0.