Charlie MacDonald's first-half strike ended Sheffield Wednesday's unbeaten start to the season as Brentford won 1-0 to climb off the foot of the table.
MacDonald struck five minutes before the interval when he collected Craig Woodman's cross, swivelled and tucked a low shot past Nicky Weaver and into the net.
The Bees were previously without a win but fully deserved all three points.
Robbie Simpson had a shot cleared off the line by Mark Beevers and also struck the crossbar with a dipping volley, while Weaver pulled off a fine save to keep out substitute Nicky Adams' fierce drive.
Marcus Tudgay came closest for Wednesday but his shot was comfortably saved by Ben Hamer.