Plymouth moved back into League One's top six with a comprehensive 4-0 win over mid-table Southend thanks to two goals apiece from Ruben Lameiras and Graham Carey.Lameiras opened the scoring, finishing off a brilliant passing move by steering a low shot past United keeper Mark Oxley after being teed up by target man Ryan Taylor.Simon Cox missed a golden opportunity to level when Argyle keeper Remi Matthews could only parry Dru Yearwood's thumping 30-yard drive into his path.Southend would rue that miss as within a minute as Carey fired promotion-chasing Plymouth 2-0 ahead with an audacious, deflected strike from the right of the box that flew up and over Oxley and in.Carey doubled his tally and extended Argyle's lead in the 52nd minute when he swept in Oscar Threlkeld's pinpoint cross from the byline.He missed an opportunity for a hat-trick when substitute Joel Grant won a 73rd-minute penalty after John White's foul. Carey's rising spot-kick flew off the top of the crossbar.It was left to Lameiras to make it 4-0 in the 88th minute when he pounced as Oxley failed to hold Grant's strike.