The visitors have also lost successive games in the second tier, leaving the Owls three points adrift of safety with a game in hand.
Thomas Frank would have been aware of the challenges which came with possessing such a long unbeaten run, including the ramifications of one defeat halting their progress.
However, the Brentford boss would not have envisaged three defeats in a row, particularly against a Coventry City side who had gone five matches without success.
Top goalscorer Ivan Toney was a notable absentee, but it should not be used as an excuse for a setback which has only encouraged the teams around them in the automatic promotion race.
Brentford only remain in the top two due to Swansea City's shock 4-1 defeat at Huddersfield Town, although the reprieve will not distract Frank from the job that he has in front of him going forward.
While a fixture against Sheffield Wednesday is one which Brentford should be winning, the stakes being raised over the past week will only give encouragement to their opponents in midweek.
Wednesday have their own issues to contend with having suffered back-to-back 1-0 defeats against Stoke City and Birmingham City, teams who had been on lengthy winless streaks before their respective victories.
The most recent setback was partly due to the Owls playing at a man disadvantage for the majority of the second half, but Neil Thompson was left frustrated with not being able to take advantage of a winnable fixture at Hillsborough.
Wednesday have still collected nine points from their last six outings, the 11th-best return in the division over that period and on par with their next opponents.
Nevertheless, there is a feeling that this is a pivotal point for both the club and caretaker boss, who may feel that he will be replaced if his side do not stay within touching distance of safety.
Brentford Championship form: WWWLLL
Sheffield Wednesday Championship form: WWLWLL
Brentford defender Rico Henry has joined Toney on the sidelines after suffering a hamstring injury against Coventry on Saturday.
Wednesday will be without Liam Shaw after the midfielder was dismissed against Blues for two yellow cards.
Thompson could opt to revert to three at the back, putting Adam Reach in line to feature at left wing-back.
Brentford possible starting lineup:
Raya; Dalsgaard, Pinnock, Sorensen, Rasmussen; Dasilva, Jensen, Janelt; Mbeumo, Forss, Canos
Sheffield Wednesday possible starting lineup:
Westwood; Lees, Dunkley, Urhoghide; Harris, Pelupessy, Hutchinson, Reach; Bannan; Rhodes, Paterson
We say: Brentford 2-1 Sheffield Wednesday
Both teams will have nerves heading into this encounter as they bid to improve their recent results. While the visitors could potentially make things difficult for Brentford, we feel that the Bees will show a greater cutting edge in this contest, particularly when it comes to pushing for all three points in the closing stages.