Two Josh Wright goals in the space of four first-half minutes secured Gillingham a 2-1 win over 10-man Southend.
Wright fired home twice in quick succession before the Shrimpers were reduced to 10 men deep into first-half stoppage time, when Ryan Inniss was dismissed after being shown a second yellow card.
Southend rallied in the second half, with substitute Nile Ranger heading home but Wright's double saw the Gills come out on top.
Wright's first goal of the afternoon came from the penalty spot in the 41st minute after Southend defender Jason Demetriou brought down Cody McDonald.
Wright fired the penalty into the bottom-left hand corner of the net and then doubled his tally in the 45th minute when he bundled the ball home from close range after excellent approach play from McDonald.
Before the break Southend suffered a further blow when Inniss committed a foul and was shown a second yellow card.
The play-off chasing visitors fought hard in the second half and netted a late consolation when Ranger nodded home Theo Robinson's right-wing cross.