Danny Cowley was left cursing a controversial decision and the lack of a clinical edge at Plymouth.
Ryan Hardie netted the only goal of a close contest in Devon to ensure Pompey’s eight-match unbeaten run came to a close.
That came midway through the second half and the visitors responded by applying plenty of late pressure.
But there was little to test Michael Cooper between the sticks and Cowley knows his side have to do better in front of goal.
The Blues boss said: “There was very little between the two teams and credit to Plymouth for coming out on the right side of a tight game.
“We’re obviously bitterly disappointed with the penalty decision at 0-0, which had a huge bearing on the match.
"I felt we gave absolutely everything and fought really hard, although it’s fair to say we lacked some quality with our final action."
“I spoke to the referee and he apologised because it was a clear foul, with their keeper kicking George and not the ball.
“We then lost the ball for their goal and mistakes happen, but our response off the back of that was excellent.
“I felt we gave absolutely everything and fought really hard, although it’s fair to say we lacked some quality with our final action.
“Up until we got ourselves into that part of the pitch, I thought it had been a very positive performance from us.
“We’ve had enough good moments away from home and perhaps those chances just fell to the wrong people on the night.
“But I know this group are giving their all – they’re playing with a lot of heart, fight, courage and togetherness.”