Izale McLeod struck a late equaliser at Coventry to earn Portsmouth their first point in eight matches.
Alex Cisak, making his debut in the Pompey goal, made several fine saves to deny the Sky Blues early on.
But his goal was eventually breached when Gary McSheffrey latched on to James Bailey's pass and slotted home.
David McGoldrick thought he had sealed it only to be flagged offside, leaving McLeod to nip in and take advantage of a defensive mix-up to steal a point.
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Sky Blues boss Mark Robins told BBC Coventry & Warwickshire:
"I thought we were outstanding in the first half. We had the lion's share of the play and the chances. We should have taken more chances because when you're 1-0 up you always run the risk of conceding in the fashion that we did at the end.
"The run that we're on continues, and there's still plenty of work to do, but things have certainly improved over the past week or two. We've got to the stage where we've learned to pass the ball properly to each other.
"We've got to the stage where we know that we're going to score goals and we know that we're going to perform in front of our supporters. In conceding the goal we were a little bit naive. There was a communication breakdown."
Portsmouth caretaker manager Guy Whittingham told BBC Radio Solent:
"You keep putting the ball in the box, you'll get a chance sooner or later.
"And it was a great ball from Adam Webster and a great finish from Izale McLeod.
"We believed we could do it [end the losing run]. We told the lads to keep believing they could do it.
"It means everything for us that we've stopped that run of results."
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