Bryan Mbeumo's double and a goal by Yoane Wissa earned Brentford a comfortable 3-1 home win over promoted Southampton in the Premier League on Saturday.
Brentford, who beat Crystal Palace 2-1 in their season opener but lost to Liverpool 2-0 last weekend, moved up to fifth on six points while Southampton are 19th and still without a point.
Mbeumo put the hosts in front just before halftime with a simple low finish, following up on Kevin Schade's strike which bounced off the post.
He doubled the advantage in the 65th minute with a first-time shot into the bottom corner of the net.
Brentford profited from another defensive error by Southampton, who lost the ball just outside the box and Mathias Jensen played in Mbeumo with a precise pass for his third goal in three Premier League games.
Wissa bundled the ball in past Southampton keeper Aaron Ramsdale four minutes later, making it 3-0 after Nathan Collins headed the ball on from near the back line following a throw-in.
Ramsdale started for Southampton one day after finalising a four-year deal from Arsenal.
Southampton made two attacking substitutions at halftime, introducing striker Cameron Archer and midfielder Mateus Fernandes but they managed only two shots on target after the break.
Defender Yukinari Sugawara scored a consolation goal in stoppage time for the visitors, who lost their first three games of a league season for the first time since 2012-13.
They host Manchester United on 14 September while Brentford travel to champions Manchester City the same day.