He smashed over the bar of an open goal from eight yards with six minutes on the clock and then ended the game with a poor miss with a header which barely tested Joe Lewis in the Cardiff goal.
"He has got to stay at it," said Bruce, who, aware of Hull's anaemic front line, made a late and ultimately unsuccessful deadline-day move for West Brom's Shane Long.
"Danny has to stay strong. I just spoke to him about that. If you're a striker, you go through these spells. You don't lose your ability, but you have to stay strong. That's the Premier League, it's tough.
"I'm not going to single anyone out. A striker is judged on goals. He's finding it difficult but perhaps that's why he's here. He needs one to settle him down. Perhaps he's trying too hard because his overall game was terrific. He needs one to go in off his backside.
"Who knows, he could go and score the winner against Newcastle next week."
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