Jon Nolan’s goal two minutes before the break sees the Blues go in 2-1 behind at half-time at Portman Road, Portsmouth having netted two goals in two minutes earlier in the period.
Town boss Paul Lambert made nine changes with centre-halves Toto Nsiala, who skippered, and Mark McGuinness the only players to survive from the team which lost 2-1 at Sunderland on Tuesday.
David Cornell was in goal with Janoi Donacien at right-back and Myles Kenlock on the left of the defence.
In midfield, Nolan was back after his suspension and joined Emyr Huws and Brett McGavin, who was in Andre Dozzell’s usual playmaking role.
Up front, Oli Hawkins, facing his old club, played down the middle, with Freddie Sears on the left and Keanan Bennetts making his full senior debut on the right.
Striker James Norwood was back on what was a very Town strong bench after his hamstring injury.
Portsmouth named the same team which beat Lincoln 2-1 at Sincil Bank on Tuesday evening with ex-Blues frontman Ellis Harrison on the bench.
Town dominated the opening period of the game, but were largely passing it around in their own half of the field without threatening to create an opportunity with Portsmouth’s pressing and preventing them from getting into danger areas.
Perhaps inevitably, the visitors took the lead with their first attack of the game in the 11th minute.
McGuinness fouled Ryan Williams not far outside the area to the right and Ronan Curtis, who scored the goal which won Pompey the only league meeting between the sides last season, took the free-kick.
The Irishman’s strike beat the wall, Cornell palmed it on to the post but it appeared to hit the keeper again on his back and cross the line.
Two minutes later, it was 2-0. Town had been forced to go long after passing it around in their own half but it had quickly been returned. Eventually, Andrew Cannon cut it back from the right to the edge of the box and Pompey skipper Tom Naylor hit a low shot which deflected off McGuinness, who has had a tough week, and past Cornell to his right.
Town seemed a little shellshocked at suddenly finding themselves two goals behind and weren’t able to threaten until the 21st minute when Bennetts, who had made a positive start to the game, crossed from the right for Hawkins, who sent a header looping wide.
Portsmouth were forced into a change two minutes later when Cannon limped off having undergone treatment. Ben Close replaced him in midfield.
On 28 Hawkins was shown the game’s first yellow card following an aerial challenge with Rasmus Nicolaisen.
The Blues were continuing to see most of the ball but Pompey looked likely to score every time they broke forward towards the Town goal.
As the half-hour mark approached, a counter-attack of just that variety saw Close feed Curtis, who hit a shot from 20 yards which Cornell pushed past his right post.
The Blues played themselves into trouble in the 33rd minute when Cornell was closed down by Curtis just inside his area after an Nsiala backpass and kicked weakly straight to Marcus Harness. The former Burton Albion man probably should have shot first time towards the empty net but took the ball on and was eventually crowded out.
Despite continuing to dominate possession, Town hadn’t looked like scoring at any point until Nolan pulled a goal back out of virtually nothing in the 43rd minute.
McGuinness played a long ball forward for the Liverpudlian as he made a run into the box. Nolan’s first touch sent it to his left towards Sean Raggett, who inadvertently returned it to the unmarked midfielder midway inside the area from where he hit a shot on the turn which beat the previously untested Craig MacGillivray in the Portsmouth goal.
The goal was the final action of a half in which the Blues had seen an awful lot of the ball but without being able to do much with it until Nolan’s late goal which owed more to poor defending than Town’s patient build-up play.
There may have been an element of good fortune about both Pompey’s early goals, however, they had looked like scoring on almost every occasion they had broken forward and might well have been more than two goals in front prior to Nolan’s first for Town.
Town: Cornell, Donacien, Nsiala (c), McGuinness, Kenlock, McGavin, Huws, Nolan, Bennetts, Hawkins, Sears. Subs: Holy, Wilson, Judge, Lankester, Edwards, Jackson, Norwood.
Portsmouth: MacGillivray, Johnson, Nicolaisen, Raggett, Pring, Williams, Naylor (c), Cannon (Close 23), Curtis, Harness, Marquis. Subs: Bass, Downing, Mnoga, Morris, Hiwula, Harrison. Referee: Andy Haines (Tyne and Wear).