Southampton was left still searching for a reaction after being soundly beaten 3-0 at Brentford on Saturday.
Pontus Jansson and Yoane Wissa scored just one minute and 18 seconds apart, before Kristoffer Ajer confirmed all three points with his second-half goal.
Adam Armstrong, who was finally handed a start, thought he pulled one back for Saints approaching half-time, but was deemed to be in an offside position in the build-up.
Ralph Hasenhuttl has come under fire for his side’s play of late and was greeted with, “You don’t know what you’re doing”, chants when he subbed Stuart Armstrong for the defensive minded Oriol Romeu in the 83rd minute.
The win will assist Brentford in consolidating their efforts for a mid-table finish in their first season back in the top-flight of English football.
Brentford was fully deserved of their lead when Jansson turned in Ivan Toney’s cut back from a Christian Eriksen corner-kick in the 13th minute.
The Bees didn’t have to wait long to double the advantage as Wissa raced onto a loose ball and fired past a diving Fraser Forster just 78 seconds later.
Saints threatened after falling behind 2-0, but their struggles in front of goal continued as Armando Broja and A. Armstrong were left frustrated by missed chances.
Brentford always looked like pushing the game out of reach more than Saints looked like getting back into it after the break and Ajer made it 3-0 late on when he fired in Christian Norgaard’s pass.
Brentford (4-3-3): Raya; Henry, Bech Sorensen, Jansson, Ajer; Eriksen, Norgaard, Jensen; Wissa (Dasilva 68), Mbuemo (Baptiste 81), Toney
Unused subs: Lossl (GK), Young-Coombes, Roerslev, Stevens, Jeaniver, Fosu-Henry, Janelt
Goals: Jansson (13), Wissa (14), Ajer (79)
Southampton (4-4-2): Forster; Perraud, Salisu, Bednarek, Walker-Peters; Redmond, Diallo (Elyounoussi 64), Ward-Prowse, S. Armstrong (Romeu 83); Broja, A. Armstrong
Unused subs: McCarthy (GK), Valery, Adams, Lyanco, Dibling, Tella, Long
Bookings: Diallo (17)