With promotion already assured, Brentford fell to a 4-1 defeat at Colchester United on Saturday.
Relegation-threatened Colchester grabbed a vital win as they put three past the Bees in the first half alone, before adding a fourth in a second half which saw Kevin O'Connor come off the bench to make his 499th appearance for Brentford.
Colchester had the first chance when Jabo Ibehre raced clear of the Bees defence but rushed his shot as he fired wide of the left hand post from outside the box.
The Bees first real chance came midway through the half when Jonathan Douglas' 25 yard free kick was palmed away by Sam Walker.
The home side should have taken the lead when Sanchez Watt broke down the left and set up Freddie Sears, but the striker fired wide of the post.
Colchester took the lead when Brian Wilson's dangerous free kick into the box was headed past David Button by former Bee Marcus Bean.
They had another good chance a minute later when Watt's snap shot was held by Button.
The Us doubled their lead minutes later when Ryan Dickson's corner from the right was headed home by Alex Wynter.
A lovely piece of skill saw Douglas just fail to get a toe on the end of Alan Judge's looping pass into the box, while shortly after Clayton Donaldson curled an effort just over the bar.
The Bees conceded a third when Alan McCormack's challenge resulted in a penalty and Sears sent Button the wrong way from the spot.
In added on time Brentford got a goal back when Stuart Dallas fired home from the edge of the box.
Ten minutes into the second half George Saville lost the ball on the half way line and Ibehre sprinted into the Bees' box, but his final ball was poor and Button gathered comfortably.
Sears grabbed his second after a defensive mix-up at the back saw both Tony Craig and James Tarkowski fail to take responsibility for a ball into the box and as Button hesitated too, Sears steered the ball past him into an empty net.
It just wasn't Brentford's day and with a quarter of an hour remaining after Alex Gilbey caught Judge just inside the box, the midfielder saw his spot kick saved as Walker dived to his right.
Brentford: Button, McCormack (sub O'Connor 84), Tarkowski, Craig, Yennaris (sub Clarke 81); Douglas, Judge, Saville, Dallas; Donaldson, Trotta (sub Adams 59).
Subs (not used): Lee, Reeves, Diagouraga, Grigg.