Kenny Jackett has urged his side to stop being so sloppy at the back.
There was a defensive horror show in the first five minutes of Tuesday night’s 2-1 defeat to Doncaster.
And the woes continued as errors contributed to another loss – this time a 3-0 reverse against Blackburn at Ewood Park.
Bradley Dack, Danny Graham and Craig Conway found the target as the hosts made the most of their opportunities.
But Jackett knows that Pompey need to be more difficult to breach if they want to embark on a more consistent run of positive results.
The Blues boss said: “In the end it was a case of them making fewer mistakes than us.
“It’s not always about doing something special on the ball – sometimes it’s about being dogged and making sure you do your job.
"You need to make sure that the opposition do something fantastic if they want to break the deadlock."
“It’s about Donohue and Clarke not playing two short passes, giving it away and all of a sudden you’re 1-0 down.
“If we’re going to make mistakes like that at vital times, then we’ve got to be very good at the front end of the pitch.
“You need to make sure that the opposition do something fantastic if they want to break the deadlock.
“We’ve given away five goals in two away games and that’s cost us. It should be zeros and ones in the against column, but we’ve given ourselves too much to do.
“We need to be more like Blackburn because it was a very solid performance from them and they deserve the points.
“The quality of our crossing wasn’t quite there to find shooting chances and we lacked that cutting edge.”
Storm Brian ensured that the game was played in driving rain, with wind swirling around the stadium throughout.
Jackett said: “The conditions were difficult, but it was the same for both teams, so we certainly won’t use that as an excuse.”