Sunderland defender O'Shea: Mignolet as good as any keeper I've played with
O'Shea saw the likes of French World Cup winner Fabien Barthez and Holland's record appearance holder Edwin van der Sar at close quarters in his time at Old Trafford.
He said: "Simon has been fantastic and he compares very well to the goalkeepers I have played alongside in terms of his presence, one-on-one situations and the confidence he gives the team.
"Those are the important things with a goalkeeper.
"You know if the defence is breached, then the attacking side have a big obstacle to get past again."