The young keeper has stepped in for injured No1 Tim Krul.
Pardew said: "It's a tough agenda for him because Tim is a Dutch international and a great goalkeeper, and the fans love him here, so there's always that pressure.
"But I never doubted his ability. The only problem Rob had when I first managed him was a lack of confidence.
"But we pursued him because we knew that. After I left and (goalkeeping coach) Andy Woodman stayed there, he grew as a first-team goalkeeper and confidence was all the problem was. Now he's got that.
"He's a great shot-stopper - he's one of the best, trust me - and he's finding a nice little niche here."