Middlesbrough head into the half-time break trailing Millwall 2-0 at the Riverside Stadium.
The visitors went ahead when George Friend inadvertently turned the ball past his own goalkeeper from James Henry's free kick with 25 minutes on the clock.
Tony Mowbray's men had plenty of possession but rarely troubled David Forde.
They fell further behind when Martyn Woolford applied followed up Benik Afobe's shot, which had been palmed away by Jason Steele.
The home team were greeted by a chorus of boos as they left the pitch having put in a lacklustre first-half display.