Sunderland manager Gus Poyet has claimed that new signing Santiago Vergini will be a "great addition" to the club.
The 25-year-old centre-back has joined the Black Cats on loan for the remainder of the season, and Poyet feels that he will be good competition for John O'Shea and Wes Brown.
"Santiago is a player I've been following for, I would say, nearly a year and a half," he told the club's official website.
"The type of player he is, his age, his character and the way he plays suits the way we want to play.
"He's going to be pushing John and Wes to the limit and asking for a place. He is a great addition to the mentality of the group."
Vergini has been capped once for the Argentine national side.