Brentford's nine match unbeaten run came to an end at Cardiff as two first-half goals condemned the Bees to defeat.
Joe Ralls gave the Bluebirds an early lead as the west Londoners failed to deal with a long throw.
Yoann Barbet had a good chance to level soon after but he fired over from a well-worked free kick.
The Bees should have been on level terms just after the half hour mark but what transpired was one of the worst misses you will ever see at a professional contest.
Ollie Watkins had brilliantly won the ball back and taken the ball past Neil Etheridge by squaring for Neal Maupay.
The Frenchman had the goal gaping with Sol Bamba racing to the line and, even though he could have walked it into the net inexplicably fired wide.
To compound the horrendous miss, Bruno Manga broke down the right and his cross found Danny Ward who slid the ball home.
Brentford pushed hard in the second half but failed to breach Etheridge's goal and we rate the players below.
Dan Bentley – A couple of nervous moments from Brentford's goalkeeper but, overall, it was a solid game. 6
Josh Clarke – Came in for some rough treatment but stood up to the challenge well. 7
John Egan – A typical John Egan performance as he did everything in his power to help his team. 6
Andreas Bjelland – Didn't do much wrong all game. 6
Yoann Barbet – Had a tough time out of position at left back but will feel he should have done better with his first half chance. 6
Ryan Woods – What's becoming known as a Woodsian display as he looked to dictate play throughout the 90 minutes. 7
Nico Yennaris – Made some good passes and looked to drive his side forwards. 7
Romaine Sawyers – Was surprisingly showing his anger more than I've seen him in his time at Brentford. 6
Ollie Watkins – A great tackle in the build up to Maupay's miss. 6
Neal Maupay – The Frenchman worked hard for 60 minutes but all it'll be remembered for is his horrendous miss that will be replayed on blooper DVDs for decades. 4
Florian Jozefzoon – Didn't have the impact on the game that he'd have liked. 6
Lasse Vibe - Worked hard. 6
Sergi Canos - His usual box of tricks. 6
Josh McEachran - Didn't have much time to make an impact. 6