Brentford fell four points behind League One leaders Wolverhampton Wanderers after slumping to a 3-0 defeat to Rotherham United at the New York Stadium tonight.
A first-half brace from Kieran Agard and a late Haris Vuckic goal proved sufficient in downing the Bees as Mark Warburton's lose ground on top spot.
It was the visitors who managed to fashion the first opportunity of the game as Clayton Donaldson's effort was tipped past the post by Adam Collin on nine minutes.
However, the hosts grew into the encounter as time elapsed and saw their improvement rewarded after James Tavernier won a penalty on 13 minutes. Agard stepped up and kept his composure to fire beyond goalkeeper David Button from 12 yards.
Having won the penalty, Tavernier came within millimeters of playing a bigger role in United's second after his 35th-minute free kick cannoned off the post.
Nevertheless, Agard was on hand to double the advantage shortly before the interval, capping off a free-flowing move with a clever finish to give Steve Evans's men a two-goal lead.
The 24-year-old should have collected his hat-trick on the hour mark but headed a clever Nicky Adams cross over the bar from six yards.
However, Vuckic struck in the dying embers to cap an impressive victory for the Millers.
Shane Callaghan
