Millwall captain Danny Shittu headed his side into an FA Cup semi-final against Wigan as Blackburn's season took another dismal turn at Ewood Park.
Shittu, whose only other goal this season came in the Lions' fourth-round triumph over Aston Villa, came close to scoring with a pair of spectacular long-range efforts when the first attempt to settle this all-Championship quarter-final finished goalless at the weekend.
A thumping header more akin to a robust centre-half was Shittu's chosen method on this occasion as he converted Chris Taylor's 43rd minute corner and settled the contest at 1-0.
As at the weekend, Blackburn sorely lacked creativity and £11million strike force Jordan Rhodes and Republic of Ireland international Leon Best drew a blank once more, although the latter had a second-half shot superbly cleared off the line by Shane Lowry.
Millwall now face a rematch of their 1999 Wembley defeat to Wigan in the Football League Trophy final, while results on Saturday could send Rovers into Sunday's east Lancashire derby against Burnley just three points above the relegation zone - an unthinkable second-consecutive relegation hovering ominously into view.