Brentford's stuttering start to the season continued as Mark Bradley's first-half header earned Rotherham victory to lift them up to sixth.
Bradley rose highest at the far post to power Ben Pringle's whipped free-kick past a static Bees defence early on.
Clayton Donaldson almost levelled, but his chipped effort was blocked by Millers keeper Scott Shearer.
Adam Forshaw also came close just before the break, but his rising drive cleared the crossbar.
VIEW FROM THE DRESSING ROOM
Brentford boss Uwe Rosler told BBC London 94.9:
"Frustrated are the right words, we tried but could not break them down, we knew what they are about, hard working.
"I am responsible for team selection and that's with me and I will not blame anybody else.
"We have to start to play our football again, we have players low on confidence and can't handle the pressure and the expectation and are not playing with freedom.
"We are failing to compete physically and making stupid mistakes."
Rotherham United manager Steve Evans tells BBC Radio Sheffield:
"The biggest compliment I can give to my team today is they (Brentford) have not had a chance.
"The only save of note was Scott Shearer's sensational save from 30 yards.
"And I think the whole ground applauded and that's why we play him."
Brentford 27 Button 14 Logan 38 Taylor 06 Dean 05 Craig 04 Forshaw 20 Diagouraga (El Alagui - 70' ) 12 McCormack Booked (Saville - 76' ) 07 Saunders 09 Donaldson 29 Trotta (Grigg - 45' ) Substitutes 01 Lee 17 Saville 28 Nugent 19 Fillo 08 Douglas 11 Grigg 10 El Alagui Rotherham United 01 Shearer 14 Bradley Booked 04 Arnason 03 Skarz 20 Morgan 15 Milsom Booked (Tidser - 83' ) 18 Pringle Booked 08 Frecklington Booked 22 Agard Booked 16 Tubbs (Hylton - 62' ) 09 Revell Booked (Eaves - 86' ) Substitutes 25 Eaves 23 Tidser 11 Hylton 21 Collin 31 Rowe 06 Mills 02 Brindley
Ref: Oliver Langford