Southend earned a fine victory at Rotherham with two goals from Britt Assombalonga and one from David Martin.
Southend opened the scoring when Martin's cross was headed in from just under the crossbar by Assombalonga.
Assombalonga grabbed his second after brushing aside the challenge of Ian Sharps before firing into the top corner for his ninth goal this season.
Assombalonga's shot was then touched on to the crossbar by Scott Shearer and Martin headed home the rebound.
VIEWS FROM THE DRESSING ROOM
Rotherham United assistant manager Paul Raynor told BBC Radio Sheffield:
"After that performance I can find no positives if I'm honest.
"Sometimes it's easy to find positives in games, I can't find one.
"We were disjointed. There seemed to be a lack of desire, lack of passion and we got beaten at our own game.
"Southend were excellent, they worked hard. Even their gifted players worked really hard for their team."
Southend United manager Paul Sturrock told BBC Essex:
"We've got some quality players, they've kept shape, which has been vitally important and the front two have caused mayhem.
"We've re-structured this team, it took a while for them to settle but now they are learning what the story is.
"Britt is so keen to do well, he wants to score goals, he wants to learn. He comes and asks questions about the game, where he should be in relation to where the ball is.
"I've never really had a player like that, who is so desperate to learn the game."