Brentford failed to capitalise on a stunning start against the Championship's form team as they were well beaten by a talented Cardiff side.
The Bees came out brightly and should have scored inside 20 seconds but Neil Maupay drilled his shot straight at Neil Etheridge.
The French striker made amends when he beat Cardiff's offside trap to slot in after being put through by Sergi Canos in the fifth minute.
Dean Smith's men were in the ascendancy with Maupay and Ollie Watkins having shots blocked in the box in the ninth minute.
The Bluebirds then started to exert pressure of their own and Dan Bentley saved well to deny Callum Paterson and Junior Hoilett.
Cardiff were not to be denied for much longer - on 25 minutes, Sol Bamba hit a 20-yard stunner that gave Bentley no chance.
Neil Warnock's men snatched another when Paterson converted a low Hoilett cross from the left flank, after an error from Josh Clarke, in first half stoppage time.
Brentford came out fighting in the second half and had a penalty shout denied by the ref when Bamba appeared to check the run of Maupay.
But it was Cardiff who struck again through Kenneth Zohore, who took advantage of sleepy Bees defending to poke home on 58 minutes.
The Bluebirds nearly grabbed another in the 65th minute when Zohore's looping header forced Bentley into an acrobatic save.
Brentford had chances to reduce the deficit but let Cardiff off the hook in the 83rd minute when John Egan fired wide from five yards and that was all she wrote.
Below are five talking points to emerge from the game
Not physical enough
Ever since they've been promoted to the Championship, Brentford have struggled against sides that boast a powerful physical presence.
They may have played 'pretty' football but when up against a side that likes to bully opponents physically they have often been found lacking.
The third goal was a mark of that. The Bees defence stood off Cardiff and allowed Kenneth Zohore to score.
Brentford have lacked a player opponents hate facing as a first team regular for some time. Alan McCormack was that sort of player but he would not get into the team now.
A phrase you hear in the game often is 'football is a results business', although it is normally used when referring to a manager at risk of the sack.
Results also mask performances. You can point to the pass count, possession and shots on goal but, if you've not won the game, that's what people remember. An example used previously was Brentford's 1-0 win at MK Dons where they got battered for 90 minutes and scored with their only shot of the game.
Game management needs to improve
For the second successive game, Brentford were guilty of overplaying it at the back and were punished for it.
In the first minute at Millwall, they tried to play it out from the back and were punished inside the first minute. It was the same again in first half stoppage time against Cardiff.
Brentford are a side that like to play it out from the back and that's ingrained in the club's philosophy but there's a time where you have to sacrifice looks for effectiveness.
Opponents look to exploit that vulnerability and have succeeded in the past two games and it has cost the club in their play-off hopes.
Those periods early and late in games are times when the phrase 'keep it simple' comes to mind.
There's a time when a clearance into Row Z is necessary and the Bees need to get a sense of the right times to play and the right times to keep things simple.
Brentford did this brilliantly at Reading in January and they need to bring it into their game more if they are to succeed.
Managing the referee
Sky pundits Sam Saunders and Danny Gabbidon felt Brentford should have a penalty in the first half for hand ball and there was another good shout for a penalty when Neal Maupay went down early in the second half.
Brentford have not had the rub of the green when it comes to 50/50 calls over the last few years and they're not a side who appear to get in the referee's ear that often.
If you compare that to a side like Cardiff, they are regularly seen in the official's ear and working on them.
Referees are human and if players can put doubts into their minds about certain tactics then it will influence their decision making.
Neal Maupay reacted brilliantly to being dropped to the bench at Millwall as he made use of his recall with a brilliant first half performance.
The Frenchman is a combative player and he gave the Cardiff defence problems throughout the evening until he eventually tired.
The striker has got the right attitude and he's someone who has a clear desire to improve. Brentford are seeing a confident Maupay as seen by his coolly taken goal; his 10th of the season.
There's plenty more to come from him over time and he is making good progress in adapting to English football.
However, come the summer, Brentford will need to find a number nine who can give him support as well as push him further.
Romaine Sawyers has been showing his class once again in the middle of the park.
The midfielder has been in fine form for the Bees this season and has become a crucial cog in how Brentford go about their business.
It's a testament to his attitude that he continues to find steps to push forward and showcase his qualities.
Along with Ryan Woods, Sawyers is now one of the first names on Dean Smith's team sheet.