Pompey have produced arguably their two best performances of the season in their most recent couple of games.
But Kenny Jackett knows his side cannot hide from the fact that they could only draw with both Bristol Rovers and Oxford.
Late goals were conceded in each of those contests, as their opponents dramatically denied them victory.
And Jackett wants to see more improvements when Southend visit the south coast on Tuesday evening.
The Blues boss said: “It is frustrating because we’ve got ourselves in good positions and haven’t been able to close things off.
“But you have to persevere and keep working your way through it, trying to become the side that’s scoring late, rather than conceding.
“We’ve netted 16 times in 14 games and definitely need to up that, while the goals against column isn’t too bad.
"We can’t just say that we played well and didn’t get the result – that’s not good enough."
“The standards have gone up a bit at Bristol Rovers and on Saturday, but we have to keep raising the bar.
“We can’t just say that we played well and didn’t get the result – that’s not good enough. You have to get over the line.
“Wherever we’ve reached in the past few weeks, then we have to raise our performance again on Tuesday night and try to go one better.
“We want to do well for the fans, for the club and for each other, so we have to take what we’re doing well and look to build on that.”
The Shrimpers are managed by Pompey’s FA Cup-winning captain Sol Campbell, who is being assisted by former Fratton team-mates Hermann Hreidarsson and Andy Cole.
They have won just one league game all season and find themselves eight points adrift of League One safety.
Jackett said: “Sol’s good enough to take on the challenge and I’m sure he’ll be working hard and looking positively to the future.
“Wherever a side are in the table, we know we’ll have to work hard to overcome them and get the points.
“It doesn’t matter whether they’re in-form like Oxford were on Saturday or currently in the relegation places.
“We’ll respect them, understand their strengths and weaknesses, but try to impose ourselves on the game and raise our own standards.”