Marcelo Bielsa's side once again left The Den without victory for a sixth game running, a record which stretches back to March 2012.
Gaetano Berardi was handed his marching orders after just 14 minutes on Saturday afternoon as he was controversially sent off by James Linington.
The 30-year was adjudged to have brought down Lions forward Tom Bradshaw inside the box which handed the hosts the advantage as Jed Wallace converted from the spot.
Marcelo Bielsa refuses to criticise referee after 10-man Leeds United lose at Millwall, but highlights three big decisionsBradshaw then doubled the lead on the stroke of half-time before Gjanni Alioski gave United hope after the interval.
Bielsa, though, saw his outfit defeated in the capital for a second weekend running with the Leeds owner voicing his displeasure on social media afterwards.
"It's frustrating to see how many points we miss because of wrong decisions against us," Radrizanni tweeted.
"We will fight hard and come back stronger ...we can’t just wait for VAR to reach our goal. #MOT"