Pompey piled the pressure on their League One automatic promotion rivals by battling from behind to defeat Coventry at Fratton Park.
Despite trailing at the interval, goals from Tom Naylor and Brett Pitman ensured the Blues leapfrogged Sunderland and Barnsley – for a short while at least – into second spot.
Kenny Jackett’s side’s victory was their seventh successive in the league and yet again displayed resolve and steel to remain in the race for the Championship.
Pompey came agonisingly close to taking the lead in the seventh minute through what would have went down as a goalkeeping error.
Lee Brown's inswinging corner was punched towards his own net by Lee Burge, only for ex-Blues defender Tom Davies to clear off the line.
And it was the visitors who took the lead just two minutes later.
Bright Enobakhare drove through the middle under no real pressure before slipping in Hiwula, who fired a right-footed shot past home stopper Craig MacGillivray.
Jackett’s troops were then given a huge let off in the 19th minute. The Sky Blues broke on the counter-attack, with Luke Thomas rounding MacGillivray.
However, Nathan Thompson made up ground to superbly thwart Thomas’ shot on the line.
Pompey started to improve and perhaps should have levelled 12 minutes before half-time.
Brett Pitman’s cross was met by the unmarked Tom Naylor at the near post, but he headed over the bar.
Seeking added energy, Jackett made a double substitution at half-time, with Ronan Curtis and James Vaughan replaces Gareth Evans and Oli Hawkins.
In the 56th minute Jamal Lowe whipped in a teasing cross that found its way to Lee Brown at the back post, but his effort missed the target.
On 65 minutes later Lowe stood up a cross for Vaughan but he couldn’t quite adjust in time and headed wide.
However, the equaliser did arrive just a minute later. Brown floated a corner into a dangerous area and Naylor rose highest to emphatically head home.
Brown’s cross across the six-yard box in the 70th minute completely evaded everyone.
Two minutes later, Mark Robins’ troops almost regained the lead when Thomas was slipped in but shot wide when under pressure from Brown.
The game continued to ebb and flow, with both sides pushing for a winner.
In the 82nd minute, Lowe forced a good stop out of Burge – and Pompey took the lead a minute later.
Brown’s corner was picked up by Curtis at the back stick and his delivery wasn’t dealt with.
The loose ball fell kindly for Pitman, who crashed home a half-volley with aplomb.
Former Fratton favourite Conor Chaplin came off the bench in the 75th minute as Coventry looked for a leveller.
But, in truth, Pompey defended their advantage superbly, with MacGillivray rarely tested.
The win moved the Blues up to second, with both Sunderland and Barnsley kicking off at 3pm at Peterborough and Plymouth respectively.