However he made up for in minutes later when a rare Griemink mistake, after Bart didn't hold onto what looked like an easy save. Owusu made sure he didn't miss this chance.
At half time Bobby Howe came off injured, and was replaced by Alan Young.
In the second half Swindon had more of the ball, and Adam Willis had a shot cleared off the line.
Mid way through the second half Brentford made it 2-0 after Lloyd Owusu took the ball around Griemink who was on the edge of his box, and scored into the open net.
Brentford also came close again 3 minutes into injury time.
Overall a fairly poor game, Swindon now face another away trip on Saturday this time to another team looking for a play off spot - Huddersfield.
Have a look at the Brentford site to see what they say about the game.
Brentford Mad