Piquionne then had a header beaten away by Jaaskelainen as the Portsmouth pressure mounted.
And they levelled on 68 minutes when Cahill was slow to deal with a bouncing ball 18 yards from his own goal, allowing Utaka to nip in front of him and drill the ball across for Dindane to gleefully knock home from close range.
Bolton then woke from their slumbers.
Wilshere jinked his way into the box and almost set up a third home goal for Klasnic.
Tommy Smith cleared a Kevin Davies header off the line and Davies was again denied when another header hit the post deep into stoppage-time.
But despite the massive disappointment Bolton, who themselves have only won one of their last six matches, are highly unlikely to go down.
Bolton manager Owen Coyle: "We are not safe. We are nine points ahead and people can tell me about goal difference and everything else. But we have not done it yet. We need another point minimum.
"We could have done it and that is the disappointing thing. We should have put the game to bed. But we were nervous. I don't know if that came down from the stands as the club has been scrapping to stay in the league in recent years.
"I have stressed to the players, that's not what I want at this club. I do not want players who are just happy to be in the league.
"I want the players who have the energy and desire to push us up the league. That is what I am striving to do. Everyone has left disappointed because we had the game won."
Grant vows to keep fighting 'on and off pitch'
Portsmouth boss Avram Grant: "It was easy to score against us in the first half.
"But in the second half we showed good character. We never gave up, we scored two goals and should have got some more. We played some good football. I am delighted.
"In the first half we were very slow with the ball but in the second half we were good with the ball.
"In a situation like ours it is very easy to give up and wave a white flag but we will not give up. It is an unbelievable season."
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