Craig Gardner has played alongside some of the greatest keepers in the English game - and insists Simon Mignolet is now ranked right up there with them.
Gardner was a team-mate of Brad Friedel at Aston Villa as well as current England number one Joe Hart during a spell with Birmingham City.
But the midfielder has been just as impressed with Mignolet, who has developed into one of the Barclays Premier League's top stoppers since joining from Belgian club Sint-Truiden in summer 2011.
Indeed, Gardner says the big keeper's progress has been such that he can now be considered "world class" as the custodian closes in on 100 appearances for the club.
"I've been so fortunate throughout my career to play alongside some top keepers," he added.
I've played with Brad and Joe and they're great - Simon is in the same category.
"People say that Joe is the best keeper in the world; I think that Simon's definitely up there with the best and I'm sure other people will agree.
"His saves against Arsenal were immense."
Meanwhile Gardner believes Sunderland now have a bigger threat at the other end of the pitch following the £5m acquisition of Danny Graham from Swansea.
"Danny's a class act," he said. "You can see when he comes onto the pitch he works his socks off and he's there sniffing out chances and looking for goals.
"We've got [Steven] Fletcher up front and [Stephane] Sessegnon firing balls forward. There's competition for places all over the pitch which is a good thing for Sunderland Football Club."