Kenny Jackett has told Luke McGee: Pick yourself up and go again.
The Pompey goalkeeper’s blunder handed Bury all three points in Saturday’s trip to the Shakers.
On 68 minutes, McGee was caught out by striker George Miller.
The Tottenham Hotspur academy product attempted a Cruyff turn to get away from the Middlesbrough loanee inside his own six-yard box, after receiving a back pass from Matty Kennedy.
However, Miller alertly read McGee’s decision.
The Bury forward nipped in to steal the ball, with his interception rolling into the empty net.
It proved to be a moment to forget for the 22-year-old at Gigg Lane.
Jackett admitted the error was a crucial moment in the game.
But the Blues manager believes McGee needs to forget about the incident and learn from it.
‘That’s football and that’s goalkeeping – that is the way that it is,’ said Jackett.
‘He’s taken a chance obviously in the wrong area and it has been a crucial moment.
‘For him, that is part of it.
‘He has to pick himself up and needs to go again.
‘Obviously, it is a key moment.
‘He knows that it was a key mistake.’
McGee had little to do before his costly error against the League One basement side.
The shot-stopper swallowed up a couple of tame shots in the first half but was never forced to thwart a decent effort.
Pompey were given a warning seconds earlier before conceding, though, when that man Miller had an effort cleared off the line by Brett Pitman following a goal mouth scramble from a Bury corner.
McGee has been the Blues’ No1 keeper during his maiden campaign at Fratton Park.
Since completing a summer move from Spurs, he has made 50 appearances and registered 15 clean sheets in all competitions.
Jackett felt the bobbly playing surface at Gigg Lane wasn’t the sort of pitch to take risks on.
And he rued the position to attempt a such a piece of skill.
The Pompey manager added: ‘It’s obviously a mistake from Luke.
‘It’s not the pitch or, quite frankly, the position to take chances.
‘He’s taken a chance to try to turn.
‘It was a very bobbly pitch and Miller has read it and toe-poked it in which, in the end, has been the decisive goal.
‘We’ve given Bury the chance there to be honest.’
– WILL ROONEY