Emiliano Marcondes will have learnt from his first Championship start for Brentford at Millwall.
The Dane failed to make the impact he would have wanted but, at the same time, he had limited service from those in midfield.
That forced him to drop deeper to try and receive the ball and the Bees looked better as a team in the second half and when Neal Maupay came on.
Smith said: “He will have learnt from it. We probably didn't help him in the first half. We broke their press a number of times and then came backwards and allowed them to put men behind the ball.
“There wasn't room in there and he had to go searching for the ball a number of times.
“We weren't aggressive enough in the first half and that was the message at half-time. We were a lot more aggressive in the second half.”
Whoever Smith picks tonight will have to perform as it will take a performance from the whole team to claim three points against Cardiff.
He added: “We have to play as well as we can. Every man on the day has to be up there and be a seven or an eight.
“We've got committed players and work hard but if we show quality on the ball we can hurt them.”
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