Mihailo Ivanovic and Ra’ees Bangura-Williams linked up for the second consecutive match to secure a 1-0 win for Millwall, bringing a feeling of familiarity to the fans.
Ivanovic found the back of the net with a superb strike following a pass from Bangura-Williams in their previous victory against Luton Town. The duo continued their successful partnership at Portsmouth, helping the Lions secure crucial back-to-back wins on the road.
Despite dominating possession, Portsmouth failed to score and suffered their first home defeat in seven games, leaving them just two points above the relegation zone.
The match was originally scheduled for November, but a last-minute floodlight problem led to a postponement.
Early in the game, Bangura-Williams missed a clear opportunity to score from close range, squandering a perfect low cross from Aaron Connolly. In the 18th minute, Ivanovic missed a header from a corner despite being unmarked.
However, the duo redeemed themselves just before half-time as Bangura-Williams played a precise pass behind the defense for Ivanovic to score the decisive goal. Bangura-Williams recorded his third assist in as many matches.
Pompey found themselves trailing at half-time for the first time at Fratton Park since September, but their strong performance in terms of shots and possession did not translate into goals.
Portsmouth relied on crosses into the box, but failed to convert their chances, with Millwall's sturdy defense preventing them from capitalizing on their 65% possession.
In the second half, Portsmouth struggled to create clear-cut opportunities, with their attacks lacking the necessary cutting edge. Millwall's solid defensive display frustrated Portsmouth's efforts to equalize.
The hosts' best chance came in the second half when Matt Ritchie's header narrowly missed the target. Millwall goalkeeper Liam Roberts had a quiet night thanks to the team's resolute defending.
In stoppage time, Colby Bishop missed a headed chance for Portsmouth, summing up their frustrations as they failed to break down Millwall's defense, who have conceded just 14 goals on the road this season, a record bettered only by the league's top four teams.