Striker Fraizer Campbell is backing Michael Turner to make a major impact at Sunderland this season.
The two men spent much of the 2007-08 season together at Hull after England Under-21 international Campbell was sent out on loan by Manchester United.
Campbell said: "People have talked about him being one of the best defenders outside the top four clubs and I think he can definitely live up to that reputation."
He added: "I'm sure he will be a big success here.
"He's just what managers and fans look for in a centre-half. He is big, strong, he wins his headers and he is prepared to put his body on the line for the team.
"He's a very down-to-earth, honest guy and he gives you 110% in every game."
Turner's arrival represents something of a coup for Sunderland, who were one of a number of clubs chasing the 25-year-old's signature.
He was the defensive rock upon which Tigers boss Phil Brown built a successful promotion charge two seasons ago, with Campbell's goals helping fire the club into the Barclays Premier League.
Campbell told the Sunderland Echo: "He was one of the key players down there when we won promotion and he showed last year in the Premier League just how important he was to Hull.
"He will be a big loss to Hull, but a big gain for us. The manager has talked about bringing in stronger and more physical players, and Michael definitely fits into that category."