Sean Raggett insisted that Pompey deserved more from their League One visit to Oxford.
After Michael Jacobs cancelled out Luke McNally’s opener, a harsh red card for Joe Morrell meant they had play most of the game with just 10 men.
Ronan Curtis still managed to slide the visitors ahead after the break, but two late goals for the hosts ensured a 3-2 defeat.
But Raggett felt that the Blues should not have left the Kassam Stadium empty-handed after a brave performance.
The skipper said: “It’s incredibly disappointing and you could see how dejected we all were when the third goal went in.
“We’d put in so much effort and I’m proud of the boys for the shift we put in when we were down to 10 men.
"It was backs against the wall when we went down to 10 men and we had to put a new game-plan together once we got in at the break."
“They’ve hit two shots late in the game and they’re both very good finishes, but that’s how it goes sometimes.
“I don’t think we deserved that and our goals were high quality, especially when you consider we didn’t have a lot of the ball.
“It was backs against the wall when we went down to 10 men and we had to put a new game-plan together once we got in at the break.
“We executed that well and took a good chance to go ahead, but unfortunately we couldn’t quite hold on.”
Raggett was as astonished as everyone else about Samuel Barrott’s decision to dismiss Morrell for a foul on Cameron Brannagan.
He said: “The referee said it was dangerous play, but acknowledged that Joe’s foot wasn’t incredibly high and their player’s head was low.
“Quite a few of their guys were saying they didn’t think it was a red card – when you hear that from the other team, you get an idea of what the decision should have been.”