Thomas Frank says Brentford believe they can cause Manchester United further problems at Old Trafford on Wednesday.
The Bees manager saw his men thump Erik ten Hag's United 4-0 at home last August.
And while emphasising how tough an assignment he views the return fixture, Frank has also stressed Brentford's confidence that 'we can do something'.
The Dane told a press conference: 'I know it will be unbelievably difficult (on Wednesday).
'They will come flying out and fighting for every single ball. They'll be showing unbelievable determination, they'll be on top of everything, and their skillset is absolutely frightening when you look at the players they have in their squad.