The Baggies keeper was called on to make a number of saves throughout yesterday's match, including stopping a Steven Gerrard penalty.
The 29-year-old told Sky Sports News: "That penalty save probably just made it the best. I played a really good game against Chelsea at St Andrew's a couple of years ago, which we won 1-0 when Lee Bowyer scored. I played well in that game and the Carling Cup final was great when Birmingham beat Arsenal in 2011.
"But with the penalty save and the fact we were playing at Anfield, that performance probably just tops it. There was also the fact we needed the win so badly which was probably just the icing on the cake. It was a really sweet one."
Two goals in the last 10 minutes saw West Brom take the win to move above their opponents in the Premier League table.