Swindon moved second in League Two with a convincing win over fellow promotion chasers Southend.
Matt Ritchie lashed home the Robins' opener before Jonathan Smith doubled their lead from six yards out.
Jean-Paul Kalala pulled one back for the hosts - his shot deflecting off the post past keeper Wes Foderingham.
But Joe Devera's header restored Swindon's two-goal cushion before Billy Bodin netted their fourth from Ritchie's cross.
The visitors, who have now won five consecutive league games, took an early lead when Ronan Murray's effort cannoned off the right post and Ritchie smashed in the follow-up.
Winger Ritchie turned provider for Swindon's second as his cross from the right found Devera who headed across goal for Smith to nod in.
Kalala drilled in from 25 yards out to give Southend hope but defender Devera was left unmarked and headed home to make it 3-1 at half-time.
The Robins completed the rout when Shrimpers goalkeeper Glenn Morris parried away Ritchie's cross into the path of substitute Bodin, who struck low into the goal from 16 yards out.
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Southend manager Paul Sturrock told BBC Essex:
"That's the poorest performance I've been involved in on this pitch.
"I've never seen us so slow and sluggish and lethargic. We can't lose goals like we've lost tonight.
"Our back four was all over the place, our front two didn't do the job the they were asked to do, our midfield were basically chasing shadows and I'd be hopeful my goalie will put his hand up for a couple tonight.
"In the end we got what we deserved, a lot of players at this football club have got to take a right good look at themselves."