Portsmouth's hopes of a great escape remained alive as troubled Coventry's difficult week ended in defeat.
The visitors had a great chance to open the scoring when Shaun Cooper fouled Cody McDonald, but Gary McSheffrey saw his penalty saved by Simon Eastwood.
Pompey took the lead when Jed Wallace found the top corner from inside the area after combining well with Cooper.
The home side secured all three points through Patrick Agyemang's close range header following a Liam Walker cross.
With Coventry officials due in the High Court on Tuesday to face a claim for unpaid rent from the Ricoh Arena's owners, defeat was a blow to the Sky Blues' chances of ending the season in the League One play-offs.
Their first defeat under new boss Steven Pressley drops them to 10th, now five points adrift of a play-off place with just six games to go.
Portsmouth climb to 22nd, cutting the gap on Oldham, who sit just above the relegation zone, to five points.
VIEW FROM THE DRESSING ROOM
Portsmouth caretaker manager Guy Whittingham told BBC Radio Solent:
"This lifts everybody up and most of all it lifts our great fans, who were superb again.
"It was a good solid performance. I was really pleased with us defensively. When we were beaten, Simon Eastwood was capable of saving shots, so that's really pleasing.
"We know they're a good footballing side, so we had to make sure we worked hard to get close to them and stop them playing and, for the majority of the game, I think we did that.
"It's just having a settled side and players that are willing to work for each other, put shifts in, cover and tackle and be strong. When you get that spirit in your side as well, which we've built up over the last few weeks, that's a huge asset."
Sky Blues manager Steven Pressley told BBC Coventry & Warwickshire:
"We started well. In the first 20 minutes, we had real domination and a couple of big opportunities to take the lead and we didn't.
"There needs to be a greater trust with the players, and that's something we'll work towards. I'm disappointed. Not in the efforts of the group, not in their attitude, it was just their passing. We didn't dominate as much as we could have.
"It'll come. We've got a group of players who are hungry and I'm confident we'll respond to this setback.
"There's obviously been distractions, but I don't think they've had any impact on the game. There will not be any excuses. We'll continue as a to get results and get performances, and I'm sure our supporters will respond to that."