Butler has taken charge at the Keepmoat Stadium until at least the end of the season following Darren Moore’s shock exit for Sheffield Wednesday at the beginning of the week.
Despite having less than two days to prepare for the fixture, he was able to lead Doncaster to a first win in six matches, with defender Reece James netting for the seventh time this season before top scorer Fejiri Okenabirhie put them in firm control.
Jon Marquis provided a late scare for his old side with a goal off the bench deep in added time, but a dramatic block from goalscorer James saw Doncaster hang on.
The victory reignites their promotion push, moving them level on points with fifth-placed Portsmouth, who have now won only one of their past five.
Story of the match
The visit of one of their direct promotion rivals was a baptism of fire for new boss Butler, who was handed first-team duties the day before following Moore's departure.
It was especially so considering the contrast in experience between the dugouts, Kenny Jackett taking charge of an EFL club for the 817th time opposite Butler doing so for the third time, following a couple of games earlier in the season when the management team were self-isolating.
One thing that does seem to unite the two bosses is a desire to see their team play exciting football, and that was in evidence from the start. Portsmouth flew out from the kick-off as Ronan Curtis miscued his shot after good work by Ellis Harrison, while Doncaster responded with Brad Halliday stroking a volley wide from a clever James Coppinger pass.
An opening goal seemed unlikely to take long and it came in the 12th minute through a familiar source to Pompey. James scored the only goal in October’s reverse at Fratton Park, and the full-back found the net again by poking in after profiting from an exquisite, outside-of-the-foot through pass from John Bostock.
Things progressed at a calmer pace after that early flurry, both sides enjoying spells of possession without threatening the respective goalkeepers. Jack Whatmough sliced wide and Marcus Harness was denied by James at one end, while Harvey White kept out Josh Sims at the other and a crunching but excellent Sean Raggett challenge ended Jon Taylor’s night early.
Jackett took action with his side trailing at the break, making two substitutions as well as changing the formation from a 3-4-3 to 4-4-2. It helped Portsmouth establish more control after the restart and become the more threatening side for a spell, with White coming close to finding the top corner and the newly-introduced Jon Marquis almost turning in a Whatmough cross.
Doncaster were offering little from an attacking perspective, but they showed the clinical edge their visitors were lacking to double the lead with 20 minutes left. Okenabirhie did the damage with a quite brilliant strike from an improbable angle, combining monstrous power with pin-point accuracy to beat Craig MacGillivray and find the far corner.
Portsmouth still had time to mount a fightback but there seemed little energy left in them, until the very end at least. Cue two minutes of mayhem, sparked by Marquis pegging back his former club in the fourth minute of added time with a fine turn and finish.
From the kick-off they would have one chance for a leveller, and it looked like they would get it when the defence was found all at sea from a long ball forward. Step forward James, however, as the left-back threw himself in the way of White to preserve the victory in the final action of the match.
Man of the match: Reece James (Doncaster)
His attacking play has come to the fore this season and did so again with the opening goal, but James was just as accomplished at the back and frequently put his body on the line, especially at the very end.