Brentford are into the third round of the Carabao Cup after eliminating Premier League opposition in Southampton.
First-half goals from Christian Norgaard and Josh Dasilva were enough to seal victory against a full-strength Saints side.
Bees boss Thomas Frank made six changes for the south-coast clash and was only able to name five of the seven permitted substitutes.
Those available to Frank responded in style. Denmark international Norgaard escaped the attention of the home side's defence to emphatically head in his first Brentford goal from Mbeumo's 40th-minute corner.
The Bees quickly doubled the advantage as England Under-21 midfielder Dasilva sidefooted home from the edge of the box following Shandon Baptiste's cutback in first-half stoppage time.
The west London side's deserved victory sets up a third-round trip to West Brom.
Brentford join fellow London sides Fulham, West Ham and Leyton Orient in the third round, with Crystal Palace falling away at the first hurdle after a penalty shootout defeat to Bournemouth on Tuesday.
Additional reporting from Press Association
