Liverpool boss Jurgen Klopp claimed Brentford "stretch the rules" on set pieces, but admitted his side should have handled the "chaos" they created in Monday's 3-1 defeat at Gtech Community Stadium.
Thomas Frank's side deservedly earned their first win over Liverpool since 1938 as an Ibrahima Konate own goal and Yoane Wissa's header put them 2-0 up at the break.
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Alex Oxlade-Chamberlain halved the deficit five minutes into the second half as Liverpool improved, but Bryan Mbeumo sealed a famous win on 86 minutes after edging past Konate to fire past Alisson.
Brentford had two further goals disallowed for offside as Liverpool failed to deal with the home side's set-piece threat all night and Klopp said the match: "When I say they stretch the rules on offensive set pieces, don't get me wrong: that's smart.
"But they do. If you would single out all the situations, you would find five fouls. But because it is so chaotic, nobody sees it in the end. That's what they do and it's really good.
"With these set pieces, Brentford always has the chance to create chaos. That's what they do. They do that really well and I respect that a lot.
"It is really good and well organised and everything. But we had a lot of chances in not a lot. A top class game and we know we have to improve that. The second goal is a present to Brentford."
Klopp, whose side is 15 points adrift of Arsenal in sixth place in the table, also said that Brentford's third goal should have been disallowed for a foul on Mbeumo.
"It's a full throttle sprint from two players. When you then get a push in this moment you lose balance and go down. It is of course not a hard foul or whatever, but it is a little situation, but Stuart Attwell saw it differently.
"The VAR who checked it hid generally in these moments behind the phrase 'it is not clear and obvious.' Second goal decided the game, third goal shouldn't have been allowed and we should have played better."
Asked in a separate TV interview about his conversations with officials around Brentford's physicality, Klopp told BeIn Sports: "But that is exactly the same as I would talk to my microwave: you get no response really.
"It is always the same. Before the season, they give us the advice that players have to be careful in these moments because the refs will have an eye on it and then you see these games, and you see that pretty much everything is allowed.
"It is always on the edge. They use that and they accept sometimes it is an offensive foul. Today it was never. There was one offensive foul in and around a set piece in the box and we did that. Very funny."