Danny Wilson is predicting that Saturday's trip to London will see the Blades pit their wits against a promotion rival.
Brentford are currently outside the top six only on goal difference and Wilson believes the Bees are more than capable of mounting a realistic push for a place in the Championship.
They have only lost once at home in nine League One fixtures to date and ahead of United's trip south, the Gaffer has labelled it 'the sternest test to date'.
Speaking of Brentford's start to the season and their promotion credentials, Wilson commented: "At the beginning of the season, and nothing has changed to suggest otherwise, I think Brentford will be there or thereabouts.
"People often talk about them coming from out of the pack or sneaking up the blind side and they are certainly doing that.
"Uwe (Rosler) is doing a terrific job at Griffin Park, he has signed some very good players and at home they are always a tough proposition.
"Given their form of late, it is arguably our sternest test to date, they are a solid unit, but we go there confident of getting a positive result.
"Clayton (Donaldson) is an obvious threat and he scored a tremendous goal at Swindon the other night, so we will have to keep a close eye on him for sure.
"He has a terrific work ethic, but more importantly he has an excellent goals to games ratio."