Blues must play without fear and have a swagger.
LBlues go to Charlton Athletic tomorrow with that message still ringing in their ears from midweek.
Millwall was a massive game for Blues and Clark - and it was one they negotiated successfully.
The Den supposedly is 'a tough place to go.' .' But not for Blues, considering their record against the Lions, and the fearless approach.
"The players were excellent, everyone made a contribution," said Clark. "And they showed that they can do it, they can get wins.
"And they have done it, they have played well for 60 and 70 minutes of games this season.
"But you need to do it for 95, all the way through to the very end. You need to be brave.
"I said to them at the hotel, in the team meeting: 'Please, no fear. It's a pointless emotion, it's a football match.'.
"'What are you fearful for? Go and win it. If you become fearful, it works against you. Go and have a cockiness about you'.
"That's how you win football games. "Hey, you've got to be able to carry the cockiness off by getting results.
"But if you get in front, get your chest out and keep doing the right things.
"If you go two up, how have you done that? "Because you have attacked well. Don't stop attacking.
"Attack is the best way of defending, because you're in their half.
"Now, when the pressure comes on, do the right things.
"But when you win the ball back, have some composure.
"That has been the difference.
"When we have come under a bit of pressure, if and when we have won the ball back, we have given it away willy-nilly.
"We were resolute at Millwall, we weathered the storm, then we came back into the game.
"And we could have had another goal from Donaldson, Thomas scored and could also have had another one."
David Cotterill was again a star performer for Blues.
The winger's form has been rightly rewarded with a recall to the Wales squad for the forthcoming European Championship qualifiers.
Cotterill has created more chances than any other Championship player this season.
And he has an eye for the spectacular goal, too, as his strikes against Fulham and Millwall showed.
"He has been our most consistent player," said Clark.
"Crossing, right on the button. His corner delivery at Millwall was unbelievable.
"The goal he scored - wow."
Cotterill's 25-yard free-kick wobbled all over the place and dipped, deceiving the 'keeper.
"The good thing for me is he's out there practising. That's not a fluke," said Clark.
"Bag of balls every day, doing the same technique.
"Sometimes they are flying over the bar but he practices and practices so that when you talk to the young players in the group, tell them that you get better by practice, he is a good example of it.
"I talk to them all the time about the very, very top players. Ronaldo scoring his free-kicks, Beckham when he used to do it.
"They didn't just turn up on a match day and hit them.
"They're out there every day in training, 25, 30 balls, great examples - and David is terrific too."
| Wes Thomas's second-half goal |allayed any fears of another Blues collapse on Tuesday night. Inset: Lee Clark with Millwall opposite number Ian Holloway