The Blues’ progressive form stalled as they went down to a 1-0 loss at Leyton Orient last night.
Caretaker boss Guy Whittingham’s side were looking for their third win on the bounce, as they aimed to hit their best run in over two years.
But Shaun Batt’s 57th-minute strike sent them to defeat as he intercepted Dan Butler’s backpass.
The result didn’t tell the story of a game when Pompey more than matched the home side and carved out a number of decent chances.
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Ertl believes teams are now aware of the threat his side possess as they find a degree of stability on the pitch.
He said: ‘I’m disappointed.
‘We dominated the game and this defeat shouldn’t have happened.
‘But we have shown that the opponents are now thinking about Portsmouth coming to them.
‘That wasn’t a case a few weeks ago when we were struggling.
‘We came to an in-form side who are still thinking about the play-offs.
‘But we now look a strong and solid side with good shape.
‘Everyone knows their job and works hard for each other.
‘It was a good game for us in our performance.
‘I couldn’t see them scoring, to be honest.
‘We are so hungry right now and you could see it on the pitch.
‘So it’s so frustrating to lose.’
Despite the loss, Ertl believes Pompey’s display means they still have impetus going into Saturday’s trip to Doncaster.
Ertl said: ‘We are in form and this game shows we are still in form.
‘We have to take that forward with us.’