Paul Downing bemoaned a lack of quality in Pompey’s display against Cambridge at Fratton Park.
Goals from Joe Ironside and Liam O’Neil secured victory for the visitors, despite an impressive late Ronan Curtis strike.
It was a third League One loss in succession for the Blues following their reverses on the road at Wigan and MK Dons.
And with Plymouth heading along the south coast for a midweek contest, Downing is aware that they must to do better.
He said: “We’re really disappointed with the performance and result – that’s three defeats in a row now, which we know isn’t good enough.
“Going behind made the task more difficult because they came and frustrated us, but at times our build-up was slow and lacked quality.
“That then made everyone get more frustrated and we failed to create enough chances to score goals.
"There are good players at this club with a lot of experience and so we’ll use that to come back stronger."
“You train all week on how you to play, so when you go out and don’t perform, it’s obviously disappointing for all concerned.
“There’s another game coming along on Tuesday evening and we need to produce a better showing in front of our fans.
“We have to make sure we’re ready to go and start winning matches again to give them something to shout about.
“There are good players at this club with a lot of experience and so we’ll use that to come back stronger.”
Downing came into the centre of defence for his first league appearance of the season following an injury to skipper Clark Robertson.
He said: “It’s always a proud moment for me to play in front of the home fans and hopefully there’s more come.
“It would be nice to get a run of games and show everyone I’m a good player. I want to be part of a successful team.”