Brentford, who have found life in League One to be a rude awakening at times, could have no complaints about the score line.
By then the damage had been done. Yeovil took the lead on 24 minutes when Andy Welsh floated in a corner and skipper Craig Alcock moved up from the back to net with a powering header.
The second goal came on 52 minutes with Welsh becoming the scorer. Gavin Tomlin got in the way on the right and the former Sunderland man supplied a neat finish.
Alcock almost got a second goal with a header from another corner but headed against the bar at the second attempt.
It was the 75th minute before Brentford troubled Yeovil keeper Alex McCarthy when Sam Wood fired in a 25-yard thunderbolt that crashed against a post.