Gary Rowett's side have not lost in any competition this season, with cup scalps against QPR and Wigan Athletic adding to their six-match undefeated run in the league.
Burton suffered play-off final heartbreak at the hands of Fleetwood Town last term and Rowett declared his delight at his side's response to that disappointment in the build-up to Portsmouth's visit.
And his men continued their ominous march against their visitors, who themselves could have leapt into the top four with a win.
Boosted by the return of Lucas Akins from a broken hand, Burton looked in charge from the start and took the lead in just the second minute.
Adam McGurk, who netted crucial goals in last season's play-off semi-final against Southend United, put Burton ahead, directing Stuart Beavon's low cross past Paul Jones.
Portsmouth grew as an attacking threat as the game wore on and came close to levelling just after the break as Alex Wynter tested Jon McLaughlin from close range.
Burton capitalised on that let-off and doubled their lead in the 55th minute, Akins firing a low finish into the bottom corner from just outside the area.
The visitors applied some late pressure but ultimately fell to their second league defeat of the season.
