Former Pompey boss Michael Appleton saw Jorge Grant miss a second-half penalty at Sincil Bank to deny his side all three points.
Grant’s skied spot-kick arrived after former Pompey defender Nathan Thompson was penalised for handball and given his marching orders with 23 minutes remaining.
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A Timothy Eyouma own goal after 10 minutes put Peterborough in front, before Anthony Scully levelled for the Imps four minutes after the restart.
The result is one which suits the Blues with the spoils shared and the Posh moving up to fifth in the table, two points behind Kenny Jackett's men who remain third despite not featuring in the third tier since December 18.
That came against Hull, with Pompey running out 2-0 winners at the KCOM Stadium.
The result dented their hosts’ promotion hopes. Meanwhile, the second-placed Tigers’ latest outing in the division will have done little to bolster those ambitions, either.
They drew 1-1 with Sunderland at the Stadium of Light on Saturday to open up three-point advantage over the Blues.
However, Pompey can overtake them and move into the automatic promotion places if they win their game in hand.
Sunderland climbed up a place to 10th following the draw.
Another result which will please the Fratton faithful was Ipswich’s 3-2 home defeat against Swindon.
They remain eighth – a point below the play-off places.
On Friday night, Accrington moved up to sixth with a 2-0 win at Charlton.
Other results: Gillingham 0-1 Burton, Rochdale 3-3 Crewe.
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