Michael Rose scored a last-gasp equaliser as nine-man Coventry staged an incredible comeback to draw 3-3 at Fratton Park.
Coventry took the lead after only three minutes when Jordy Hiwula fired into the roof of the net after the visitors had broken swiftly from defending a corner.
Portsmouth hit back through Ronan Curtis’ header just seven minutes later before John Marquis rounded off a fine team move to make it 2-1 two minutes before half time.
Gareth Evans cashed in on a mistake by Coventry defender Kyle McFadzean to add to Pompey’s advantage in the 56th minute before Fankaty Dabo was shown a second yellow card for handball.
Matt Gooden’s penalty 15 minutes from time after Ben Close had fouled Liam Kelly reduced the deficit.
The visitors’ comeback hopes looked dashed when substitute Gervane Kastaneer was sent off after picking up two yellow cards within 11 minutes off coming on.
But Rose turned in a long throw from 10 yards four minutes from time to claim the most unlikely of points.