Brentford got the better of Reds for the second time in four days but once again they were made to work hard for their success, which this time came in the second round of the Johnstone's Paint Trophy.
Paul Jones made some good saves in the first half but Reds had their moments too and looked the side most likely to score for long stages of the second period with Jonathan Forte going closest when he hit the post.
But with 17 minutes to go substitute Sam Saunders side-footed home what proved to be the winner and Reds couldn't find a leveller, although Joe Walsh and Mark Connolly went desperately close to doing so.
Jones had made some fantastic saves on Saturday and he was at it again in the third minute when he pushed out Harlee Dean's header from point-blank range - a truly magnificent stop.
Harry Forrester then fired a 25-yard free kick over the bar and Kyle McFadzean blocked a shot from Toumani Diagouraga as the home side started on the front foot.
Forrester was booked for a late challenge on Nathan Byrne before Jones came to his team's rescue again after 11 minutes when Clayton Donaldson raced clear of the offside trap but his side-footer was pushed around the post. Jones then saved Paul Hayes' header with relative comfort but Reds got back into the game and fashioned two chances in the space of a minute.
First Sergio Torres fired just wide after good work by Billy Clarke and Jonathan Forte and then Clarke made space for an angled drive which Brentford keeper Richard Lee blocked smartly. Reds then had penalty appeals turned down after Leon Legge challenged Forte but referee Iain Williamson pointed for a goal kick instead.
It was a decent tussle at this stage as play flowed from end to end. Hayes beat the offside trap only to volley over and then Lee came to the edge of his box to smother at the feet of Forte, whose pace was causing Legge plenty of problems.
There was a bit of a lull before Brentford threatened again when skipper David Hunt gave the ball straight to Scott Barron whose cross was met with a glancing header by Donaldson which went straight to Jones.
Mike Jones then found Nathan Byrne over-lapping down the left and he cut into the box and forced Lee to push his cross-shot away for a corner just before the interval.
Jones was back in action at the start of the second half when a ricochet enabled Tom Adeyemi to find space 12 yards out but his angled drive was turned around the post by the Crawley keeper.
Mark Connolly then found a pocket of space 22 yards out to turn and shoot just wide before Clarke's effort from further out drifted wide as he aimed for the top left-hand corner.
It was hard to pick a winner at this stage as play raged from end to end. When Donaldson robbed Kyle McFadzean on 53 minutes his cross found Barron steaming in at the far post but the angle was too tight and his shot hit the side netting.
At the other end Mike Jones let fly from 22 yards but his drive whistled past the left-hand post and Reds went even closer in the 68th minute when a corner fell to Forte on the angle of the six-yard box but his shot cannoned off the near post.
The deadlock was finally broken on 73 minutes and it was Brentford who went in front when a raking cross from the left by Barron eluded the visiting defence and substitute Sam SAUNDERS stole in to side-foot powerfully past Jones, who had no chance on this occasion.
Richie Barker made three attacking changes as Reds looked for an equaliser but they had a let-off with six minutes to go when German was put clean through by Hayes' weighted pass but he side-footed wide with only Jones to beat.
At the other end Joe Walsh nearly equalised when he got on the end of McFadzean's flick on following a long throw by Hunt but the Welshman's header went straight at Lee. Reds went even closer in stoppage time when Connolly turned to fire goalwards and although his shot beat Lee, Craig was on hand to hack the ball off the line.
Brentford saw the game out and although Reds are out of the competition there were plenty of pluses for the manager as he plans for the visit of Bury on Saturday, in particular the performances of Walsh, McFadzean and Clarke.
And as for Wembley, well there's always the FA Cup isn't there!