And the Pompey boss promised supporters he’ll continue to go for the jugular against Ipswich, after bringing them to Fratton Park for a third-round replay.
The Blues delivered a fearless performance to collect a 2-2 draw at Portman Road on Saturday.
It looked as if Cook’s men were going to get the victory their performance warranted.
But a mistake from Murphy two minutes from time was the only blemish on an afternoon stacked with positives.
Cook was quick to back the man who agreed a deal until the summer on Friday.
He said: ‘I don’t want people to pick up on negatives.
‘It’s easy to do that, we have missed some chances in the first half but wouldn’t pick up on that negativity.
‘Brian Murphy is a good keeper. Come on.
‘He’s made good saves. His ball retention and distribution is excellent.
‘He’s not going to be the greatest keeper that’s ever lived. We’re playing in League Two, you know.
‘As a club we must get better and stronger and if every person we had was a top, top player we wouldn’t be in League Two.
‘But I’ll back Brian Murphy for as long as Brian wants me to back him.’
Pompey could reflect with pride on their display against a side pushing for the Premier League.
Cook said: ‘We’ve had a great result against a strong side. I would rather look at that positive.
‘I won’t have the burden of those fans travelling knowing I’m going to park buses.
‘I’ve got great faith in all of my players. We came to have a game of football and hopefully we left with credit.’