Junior Morias scored a stunner in the last minute to secure Posh all three points.
Peterborough United made it three unbeaten but more importantly they chalked up a victory as a last minute stunner from Junior Morias earned a 1-0 victory over Gillingham at Priestfield.Posh were forced into an early change as Junior Morias replaced the injured Tom Nichols who was forced off with a hip injury after a challenge in the centre circle on 19 minutes.
Marcus Maddison tested Holy with an effort from a dead ball situation on 28 minutes, the keeper making a routine stop.
The hosts then had to replace Wagstaff with Jackson, the defender suffering an injury with nobody near him.
Josh Wright headed over from 12-yards after a decent right wing centre but McGee was never likely to be troubled.
Anthony Grant was cautioned for a foul on 35 minutes by referee Mr Malone.
Referee Brendan Malone sustained an injury on 40 minutes was replaced in the middle by assistant referee Mr Wade with the fourth official taking over as an assistant.
Six minutes of stoppage time was indicated by the fourth official but like most of the first 45, not a lot occured.
The home side made a change at the break with Harry Cornick replacing Donnelly in attack. Maddison was denied by Holy on 48 minutes after a strong run and low effort on his right-foot.
Cornick fired wide of the near post on 52 minutes after cutting inside onto his right-foot as the game began to open up a tad.
Maddison sent a 30-yard free-kick just over the crossbar on 56 minutes before McCann made a second change, Paul Taylor replacing Da Silva Lopes. McGee did well to hold a towering McDonald header on 59 minutes from a right wing centre.
On 70 minutes an ambitious effort from long-range tipped over by the acrobatic Holy before Mackail-Smith volleyed wide from the angle moments later.
Wright sent a curler straight into the arms of McGee at the other end after a swift Gills counter attack. On 81 minutes, Posh carved out the clearest opportunity of the game thus far, Taylor to Smith, his perfect stand up cross picked out Mackail-Smith but he guided his header wide of the upright from close-range.
Holy gathered a Smith shot at the second attempt on 86 minutes as the right-back cut inside onto his left-foot and had a go from long-range.
McGee made a routine stop to deny a scooped effort from Wright as time ticked towards the 90 minute mark.
Just before stoppage time and Posh grabbed the lead and what a goal it was too, an absolutely stunning strike from Junior MORIAS from fully 30-yards which left keeper Holy with no chance.
Gillingham:Holy, Ehmer, Oshilaja, Wagstaff (sub Jackson 29min), Donnelly (sub Cornick 46min), McDonald (sub Parker 73min), Martin, Dack, Muldoon, Byrne, Wright. Unused subs: Nelson, Jackson, Hessenthaler, Osadebe, List.
Posh: McGee, Smith, Binnom-Williams, Bostwick, Baldwin, Forrester, Maddison, Mackail-Smith (sub Hughes 90min), Da Silva Lopes (sub Taylor 56min), Nichols (sub Morias 19min), Grant. Unused subs: Tyler, Inman, Chettle, Borg.
Half-time: Gillingham 0-0 Peterborough United
Full-time: Gillingham 0-1 Peterborough United
Attendance: 7,569 (297 Posh fans)