Danny Cowley has demanded more from his Pompey side during the final five matches of the season.
He was unhappy with their performance in an entertaining – yet frantic – 1-0 League One defeat at MK Dons.
Scott Fraser netted the only goal from the penalty spot just before half-time after Charlie Daniels had been penalised for a trip on Ethan Laird.
But there were plenty of opportunities for both sides to score more, with John Marquis and Ronan Curtis going closest for the visitors before Tom Naylor headed against the crossbar.
And Cowley admitted that he had to be careful about what he told the players following the final whistle.
The Blues boss said: “It’s been an incredibly disappointing week for us – there’s no hiding away from that.
“We created enough chances in the first half to win the game and certainly the first goal was going to be important.
“But we have to be more ruthless and clinical. There’s definitely work for us to do in that area of the pitch.
"I know it’s been a long, hard season and there aren’t many attacking changes we can make, but excuses don’t get you anywhere."
“For the first time, there was a couple of things that I really didn’t like and I had to hold my tongue a bit in the dressing room.
“It’s important to take some time to reflect and watch the match back again before you give your opinion.
“I know it’s been a long, hard season and there aren’t many attacking changes we can make, but excuses don’t get you anywhere.
“There are some who need to be tougher and show more emotional control. When things go against you, you can either look in the mirror or out the window.
“Successful people will always do the first one and look at how they can improve, so that’s my message to the group.”
Pompey had to play out the closing stages with a numerical disadvantage after Jack Whatmough was dismissed for a late challenge on Charlie Brown.
Cowley said: “The red card has compounded the defeat because Jack’s been in such good form and MK Dons are probably the worst team you want to go down to 10 men against.
“I’ve only seen the challenge live and although he did win the ball, he was off the floor and in this day and age, you can’t do that.
“It’s two sendings off in the seven games that I’ve been here, so discipline is something else we have to look at.”