French striker Laurent D'Jaffo scored the winner for Bury against Portsmouth to give them their fourth league win from four at Gigg Lane.
He headed home two minutes before the interval as Portsmouth slumped to their second successive defeat.
Both these sides were battling for first division survival last season and once again both showed tremendous fighting spirit.
Pompey forced the early pressure with John Aloisi looking lively and he was unlucky when he just failed to connect with Jamaican Fitzroy Simpson's timely cross on 17 minutes.
But, on 24 minutes, Portsmouth's Sammy Igoe felled defender Andy Woodward 25 yards from goal.
Striker Andy Preece took the free-kick and blasted the ball into the bottom corner of the net for his second goal of the season.
Preece almost added another minutes later when he tried the same from 30 yards but keeper Aaron Flahavan got his hand to it.
And it was the Bury striker again who had the chance but he turned and fired over with the keeper stranded on 38 minutes.
Five minutes before half-time Alan Ball's men equalised from the penalty spot.
Nick Daws bundled Frenchman Jean-Francois Peron over in the area and Alan McLoughlin fired to his left.
Goalkeeper Dean Kiely, who is back from international duty after Bruce Grobbelaar stood in last week, went the wrong way.
And two minutes before the interval Bury restored their lead. Rob Matthews fired in a looping corner and D'Jaffo towered above the Pompey defence to head home.
Aloisi had a couple of half chances early in the second for Portsmouth but struggled to finish as the home defence closed him down.
Bury introduced their new £200,000 buy Simon Baldry, signed today from Huddersfield, on the hour and he caused Pompey a few problems.
It could have gone either way in the final 20 minutes with the ball moving from end to end.
Aloisi was still battling for Portsmouth and D'Jaffo's long range effort fell straight into the keeper's arms.
But neither side could add to the score in a frantic finish.