Millwall mainly restricted Norwich to shots from outside of the box, but their tactic didn't work as Jonathan Howson surged forward from midfield and fired a fine strike into the top corner in the 38th minute.
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The home side then conceded a penalty shortly after as Cameron Jerome was tripped in the box, and Hooper fired the ball home just before the interval.
Norwich were keen to kill the game off after half time, and they almost found a third as Jerome went close with a header and Bradley Johnson fired an effort marginally wide.
However, it didn't take them long to score again as Wes Hoolahan latched on to a loose ball and coolly slotted it past Forde into the corner of the net.
Howson then netted his second, as the influential Jerome found him with a low cross and he easily slotted the ball into the corner.
It almost got worse for the home side, but fortunately for them Graham Dorrans's crisp shot struck the post.
Millwall pulled a goal back late on, as Lee Gregory swept in a late penalty, but it was the only thing the home fans had to cheer about all afternoon.