After registering four consecutive clean sheets at the start of this term, the Blues have seen their solid foundations at the back crumble as their League One rivals have started to take advantage.
Across the last seven days, Danny Cowley’s side have conceded 10 goals in three games in all competitions, with four more goals conceded in yesterday’s damning defeat to Ipswich Town.
Errors at the back coinciding with a lack of personnel due to injuries have added to the pile of problems the former Huddersfield Town boss is facing in PO4.
And as a result of their defensive misfortune, the club has slid down the league table while being leapfrogged by the Tractor Boys.
After calculating each League One team’s average goals conceded per match, click through the list to see how Pompey compare with their counterparts.
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1. Pompey have conceded 10 goals in their last three fixtures in all competitions. Picture: Jason Brown/ProSportsImages
Pompey have conceded 10 goals in their last three fixtures in all competitions. Picture: Jason Brown/ProSportsImages Photo: Jason Brown

2. Wigan: 0.75
Goals for: 22, Goals Against: 9, Goal Difference: +13 (Photo by Jacques Feeney/Getty Images) Photo: Jacques Feeney

3. Rotherham: 0.76
Goals for: 20, Goals Against: 10, Goal Difference: +10 (Photo by Nathan Stirk/Getty Images) Photo: Nathan Stirk

4. Plymouth Argyle: 0.86
Goals for: 25, Goals Against: 12, Goal Difference: +13 (Photo by Alex Davidson/Getty Images) Photo: Alex Davidson