But it was Millwall who had made the brighter start, taking the game to the home side. Christophe Kinet's shot from distance was tipped over by Pompey keeper Shaka Hislop in the opening seconds.
Millwall striker Steve Claridge was proving a handful against his former club and Hislop had to save smartly against former Pompey striker in the opening half-hour.
Portsmouth came back into the game as the first-half went on and Vincent Pericard's crossfield ball found Matthew Taylor who rattled the bar from 18 yards.
Moments later Pompey captain Paul Merson fed Taylor, but the left wing-back could only shoot over.
It was no surprise when five minutes into the second half when Quashie's exquisite throughball found the Millwall defence napping and Todorov advanced clear to shoot past Lions keeper Tony Warner.
Now Portsmouth started to show why they are the First Division leaders and the Millwall challenge started to fall away. First Quashie shot over from distance and Taylor poked the ball wide from a corner.
It was Portsmouth's day though as they set a new club record for the best ever start to the season.
Pompey manager Harry Redknapp was delighted: "I am pleased with three points and to continue our excellent start to the season.
"Teams are coming to Fratton Park and raising their game. Our players are not used to being top, especially the ones that have been here a while, and I thought we were a bit tense."