"We can't keep making excuses. It's the lads that have to go out there and show passion and desire."
Lewis Guy struck a first-half winner to ensure Brentford won't have another season of cup giant-killing.
The Bees knocked out Premiership Sunderland last season but were never at the races as Guy's individual goal of real class stole the show.
The former Newcastle trainee found time and space in the box on 32 minutes to fire an unstoppable low shot past Clark Masters.
The home side almost made the perfect start inside the first 90 seconds when Paul Brooker's centre from the right almost found Jo Kuffour at the near post. But Doncaster keeper Ben Smith was quick to the mark to thwart the oncoming Kuffour from getting a vital touch.
It was then the visitors turn to carve out an opening moments later thanks to some Brentford old boys.
Former Brentford front man Mark McCammon knocked a header down to another ex-Bee Jason Price only for his volley from the edge of the area to sail inches over the crossbar.
It looked like McCammon relished playing against his previous employers when he tested Masters with a flicked header from Paul Green's cross on 15 minutes.
The burly striker was certainly in the mood to silence the boos from the home crowd and he forced another save from Masters on 22 minutes, this time through a low left foot shot.
And Brentford were counting their luck from the resulting clearance which fell for Brian Stock to blast a 25-yard shot inches wide of the left-hand post.
But despite their early dominance, Doncaster were unfortunate to stay on level terms when Fola Onibuje missed a sitter from three yards.
Brentford gave a debut to striker Onibuje who was fast tracked straight into the starting line up after joining on loan from Swindon on Friday.
And from Sam Tillen's inch-perfect cross the giant striker somehow headed wide from close range despite being completely unmarked.
The miss proved to be vital as Doncaster raced up the other end to show them how it was done.
Striker Guy was given time and space in the box to send a rifling right-foot shot past the helpless Masters from ten yards for his fourth goal of the season.
Brentford's ailing confidence levels seemed to seeping through to matters on the pitch as Doncaster started the second half as strongly as the first.
Brentford had only one Johnstone's Paint Trophy penalty shoot out win over Northampton to show for in 14 previous league and cup matches and they should have been out of sight four minutes after the interval when McCammon headed Gareth Roberts' teasing cross over from six yards out despite being unmarked.
On 70 minutes, McCammon's mission to score saw him come even closer when he seemed to celebrate a goal even though he headed wide. It wasn't until he got up off the floor after diving to connect with Guy's cross did he realise the ball actually went wide of the left-hand post.
Brentford defender Kevin O'Connor tried in vain to get the home side a replay but it was not to be as his curling free-kick from the edge of the area sailed inches over.