Pompey opened up a six-point lead at the top of League One as they returned to winning ways at Fratton Park.
Oli Hawkins’ second-half header on his 50th appearance made the difference as his side grabbed a 1-0 success over 10-man Fleetwood.
That ended 50 days without a league wins at Fratton Park for Kenny Jackett’s men, as Joey Barton’s side failed to deliver a shot on goal.
It wasn’t pretty in a dreadful first half, but the Blues looked comfortable after Hawkins’ 50th-minute header to open up the six-point gap on Peterborough.
Pompey made one change as Ronan Curtis was restored in a central attacking role in place of Gareth Evans.
The first half proved a sorry affair in which neither keeper was extended.
Tom Naylor lifted a fifth-minute shot over from a tight angle from Ben Thompson’s free-kick.
It was the midfielder who fired the next chance over the top in the 18th minute, after being teed up by Jamal Lowe.
The only other noteworthy effort was Hawkins skewing his shot wide from 20 yards, in a half where his strength in winning high balls was one of the game’s few positives.
But the match swung in Pompey’s favour five minutes after the restart, as Hawkins headed in from close range after Naylor rose to head Dion Donohue’s corner goalwards.
Play was stopped with 21 minutes left when Lowe was floored after a collision with Ben Thompson, but the attacking talent was okay to continue.
Then the visitors were reduced to 10 men with six minutes left, when Nathan Sheron was shown a second yellow for a foul on Curtis.
There were six minutes of stoppage-time at the end of the game, but Pompey always looked comfortable as they saw out the win.