The Bees have accumulated nine points from their opening five Premier League games this season.
And Frank said his side will try and "find a door that is two inches open" to get a result against Jurgen Klopp's side.
Asked about Liverpool's attacking threat, Frank told the club's website: "What is so impressive is that they are an attacking threat from so many areas.
"When you are facing some teams it is mostly counter-attack or mostly crosses or something else. Liverpool are fantastic at crossing, they are fantastic through the middle, they are fantastic at counter-attacking high and deep, and they are really good at offensive set-pieces so they hit you from every angle.
"We will narrow it down and find the most important things that we think we need to match and then hopefully we can find a door that is two inches open we can put a foot in."
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!