Heaslip tells the Irish to believe ... or get out.
The team's confidence levels have been the subject of discussion, with mixed messages emerging from the Irish camp over the reason for their malaise.
So far this season they have won only three out of six games with the victories against Samoa and Italy far from resounding.
Even their record triumph against Argentina felt remarkably flat.
Defeat by Scotland at Murrayfield tomorrow would continue a worrying trend for a side that is clearly struggling in World Cup year.
Anxiety has been offered by backs coach Alan Gaffney as an explanation for their high error count, but Heaslip insists anyone afflicted by self-doubt should not be playing for Ireland.
"I don't feel any anxiousness, you'd have to ask each player individually about how they feel," he said.
"I'm pretty relaxed but at the same time a confident person. I back myself and my ability. I back any of the guys out on the pitch as well.
"I don't think there's a lack of confidence or belief. If there is, and if I know there is, I'd tell them to get off the pitch.
"You don't pull on a green jersey unless you're 100 per cent confident that you're ready to go."
Ireland's distress is elevated by the sense that they are close to producing something special, if only they can address the error count.
A series of try-scoring chances went begging in Rome while some brilliant moments against France, who were outscored three tries to one, failed to prevent a 25-22 defeat.
Heaslip accepts there are teething problems in adapting to a new expansive style, but believes they are on the right track.
"We've evolved into playing this new type of game," said the Lions No.8. "It was an exciting game when stuff clicked, we were on fire and created a lot of quick ball.
"We split a lot of teams wide open and caused them problems.
"But our own mistakes punished us, stuff like turn overs and easy penalties.
"That has happened less frequently in the 6 Nations but it has still happened one or twice. The standard of sides we're playing punish your mistakes. You might get away with it once or twice in club rugby, but international rugby is pretty ruthless.''