The Blues went down to a 2-0 loss to Notts County in today’s first-round clash at Fratton Park.
Appleton’s men were all at sea at the back for the game’s two decisive moments.
The Pompey boss was left frustrated by that in what was a low-quality game of football.
Appleton is now demanding his side put the performance right against Brentford in league action on Tuesday night.
He said: ‘The manner of the ways in which the goals were conceded was the worst thing.
‘It was a poor game of football from both sides and I didn’t enjoy watching the game.
‘After the performances we put in over the last two games I didn’t see that coming.
‘The only saving grace was it was a Cup match and there weren’t three league points up for grabs.
‘Now we have to put that right against Brentford on Tuesday.’