Just 20,440 supporters were in attendance at the 40,000-capacity stadium despite Leeds averaging 29,206 last season - by far the highest in the Championship.
Millwall fans chose not to attend the match after being offered a heavily-reduced ticket allocation following violence at last year’s fixture. And despite the huge wave of optimism which has engulfed the fallen Premiership giants this summer, many Leeds supporters also stayed away.
Blackwell, however, insisted it was not a sign of things to come and cited live television coverage of the match and the Ashes Test series, along with the summer holiday period, as reasons for the mass no-show.
While acknowledging the disappointing attendance, Blackwell was delighted to see his side overcome a spirited second-half fightback by Millwall to claim a precious victory.
David Healy converted a 72nd-minute penalty to complete his brace and cancel out Millwall debutant Don Hutchison’s equaliser shortly after the hour mark.
“We wouldn’t have won that game last season,” said the Leeds chief.
“There were many times when we were on top and let teams back into it, so it was important that we didn’t do that today.”
New Millwall manager Colin Lee took great heart from his side’s display after a turbulent summer at the New Den which has seen five key players depart and Steve Claridge sacked as manager just 36 days in the job.
But Lee has at least been able to bring in former Liverpool midfielder Hutchison on a six-month contract.
Lee said: “I felt before the game that we’d be okay today and if you look at that performance today then we won’t be struggling against relegation.”
: Sullivan, Kelly, Butler, Gregan, Harding, Wright (Richardson 80), Bakke, Derry, Lewis, Blake (Ricketts 76), Healy.
: Marshall, Lawrence, Phillips, Dunne, Vincent, Serioux (Braniff 90), Elliott (Igoe 79), Morris, Hutchison, Simpson (May 79), Hayles.
: G Laws (Tyne & Wear).