Racing Club Warwick manager Scott Easterlow blamed Sunday League defending for his side’s first league defeat of the campaign.
A poor start against their fellow promoted side saw Racers two down inside the opening 12 minutes and the away side were unable to recover.
The sending off of Danny Brain added to their woes, with Heather adding two more goals after the break to wrap up a resounding victory.
And Easterlow said his side can ill-afford to be so generous if they are to prosper at Premier Division level.
“We need to learn and learn fast that we can’t give sides a helping hand towards a result,” said Easterlow.
“The first two goals we conceded were what I expect to see at Sunday morning level, not this standard.
“Far too many lads had an off day and we can’t afford for so many all in one game to not be at the races. We ultimately paid the price for a well-below-average showing, easily our worst performance to date.
“As I have said previously, I think it would be massively naive to think we could win every game this season but the standards have to remain the same. There’s a way to lose a football match and that wasn’t it.”
There was little sign of the horror show to come in the opening minutes as Racing Club kept possession well on the long grass.
However, a mishit shot in the seventh minute found its way to Heather’s Malachi Farquharson who slotted home as Racing Club failed to react.
A few minutes later another long-range effort was palmed out by keeper Charlie Bannister and Farquharson was again there to pounce.
The second goal woke Racing Club up and Muzzy Nduna was unlucky to have a shot deflected wide, while a long-range effort from Chris Johnston was tipped over.
Nkosilathi Mzungwana had a long-range effort deflected wide, while Scott Turner was unable to convert from the resultant corner as Racing Club got on top.
However, Brain was dismissed for retaliation on half-time and the visitors were firmly on the back foot after the break.
Bannister produced a fine save to deny Farquarson his hat-trick as Heather had several chances to extend the lead.
Substitute Pierre Moudime then conceded a penalty after chopping down Kieron Clarke who picked up himself to slot home number three.
Clarke narrowly fired wide before substitute Craig Evans completed the misery in the dying seconds.
Easterlow is now hoping for a reaction in tonight’s clash at home to Lye Town and the Bank Holiday Monday trip to Coventry Sphinx.
“Maximum points now from the next two games would still see us reach the target we set out initially to try and achieve in our first five league games, he said.
“So we dust ourselves down and look for reaction.
“It just means we have no room for error now.”