Last season's Carabao Cup giantkillers Brentford almost got a taste of their own medicine before coming from behind to beat Forest Green 3-1.
Brentford, who knocked out four top-flight sides on their way to the semi-finals last year, fell behind to an early goal from Rovers' Jack Aitchison.
Now a Premier League club themselves, the Bees suddenly found themselves a potential scalp for League Two Rovers.
The lethargic hosts looked second best for long spells, in stark contrast to their buoyant display against Arsenal 10 days earlier.
Thomas Frank made nine changes from the side which drew with Crystal Palace, but few of his fringe players did anything to merit a place in the team at Aston Villa on Saturday.
But moments later the visitors took the lead when Nick Cadden – who hit a hat-trick against Crawley at the weekend – burst into the Brentford area and teed up Aitchison to fire in at the near post.
Instead Brentford equalised on the hour mark when Wissa, the £8.5million summer signing from Lorient, marked his full debut with his first goal for the club, a low drive past Thomas into the far corner.
With 15 minutes remaining Mbeumo put Brentford ahead when he met Dominic Thompson's cross with a bullet header at the far post.