John Marquis returned to the goal trail to deliver Pompey a crucial 1-0 victory over Lincoln at Fratton Park.
The big-money summer signing from Doncaster broke a 10-game dry spell to ease the pressure on under-fire boss Kenny Jackett.
The Blues delivered just a fourth win of the season as they aim to remedy the faltering start to the season.
Pompey made one change from Saturday’s 1-0 defeat at AFC Wimbeldon, with Ross McCrorie replacing James Bolton at right-back.
Former Fratton boss Michael Appleton was also in the opposite dugout for Lincoln.
The Blues threatened within two minutes when Ryan Williams’ shot on the spell was well held by Josh Vickers.
Two minutes later Marquis went for goal but his effort was easily kept out by the Imps stopper.
Pompey could count their fortunes on seven minutes when Callum Connolly was left in acres of space from a free-kick but the visiting defender headed well wide.
The game ebbed and flowed with former Blues triallist Bruno Andrade forcing a fine save out of Craig MacGillivray in the 20th minute.
From the resulting corner, the home keeper made an outstanding point-blank save from ex-Fratton striker John Akinde. The ball scrambled around the box before MacGillivray eventually gathered.
And it was Jackett’s side who made the breakthrough in the 28th minute. Vickers could only parry Christian Burgess’ powerful header and Marquis was well placed to finish the rebound from close range.
Lincoln made a decent response, with Andrade forcing a solid save from MacGillivray to ensure the hosts went into the interval ahead.
Pompey made a bright start to the second period, with Marquis and Harness linking well before Williams fired over.
In the 54th minute, Akinde should have levelled when he got in front of Raggett at the near post but was unable to get anything on Andrade's cross.
And 11 minutes later, Burgess must have thought he doubled the hosts lead when he yet again met a Evans delivery but Vickers just saved on the goal line to his left.
Then substitute Ronan Curtis’ cross found McCrorie at the far side of the box, but he blazed over.
In the 83rd minute a Tom Naylor cross was cleared only as far as Evans, although his effort flew into the Fratton End.
And while the closing stages were nervy, Lincoln didn’t threaten MacGillivray and Pompey held on for a much-needed three points
It means the Blues move up to 16th in the League One table ahead of Saturday’s trip to Bristol Rovers.