Pompey only won yesterday because they got a penalty right at the end of the game that shouldn't have been a penalty. Plus Port Vale should have had a free kick moments before that. If they had drawn that game which they should have done if the referee hadn't decided to hand them the win, they would be 2nd on GD with 3rd just a point behind. And even having been handed the win, Bolton who are 2nd and 2 points behind have 2 games in hand on them. Peterborough who are 3rd and 3 points behind have 1 game in hand and both of these teams have better goal differences than Pompey. They may well go up in the autos, they've been there all season. But it's a long way from a sure bet at this point!
Edit: Oh and Derby in 4th are also just 3 points behind Pompey in 1st also with a better GD, but have played the same amount of games.