Aldershot Town boss Andy Scott said his side had several good chances of their own but gave away sloppy goals to the visitors
Shell-shocked Andy Scott watched Aldershot Town crash to their heaviest defeat under his tenure yet insisted: "We were the better team."
The Shots boss was left helpless in the dugout after two goals in the opening 10 minutes from Lenell John-Lewis and Ross Hannah put Grimsby Town in complete control at the ESS Stadium.
And Scott's afternoon got even worse when Brett Williams had a 29th-minute penalty brilliantly saved by James McKeown before Mariners substitute Liam Hearn compounded the misery with a sublime third after the break.
"You just can't give teams a start like that," Scott moaned afterwards.
"We were 2-0 down before we even knew it and the third goal summed it up really.
"We've given three points away to a very average side. We've dominated the game but we've given them three gifts.
"People will think I'm loopy standing here saying we were the better side after losing 3-0, but that was the case.
"We've had seven or eight really good chances and then of course there's the penalty. But when you are chasing the game it's very difficult and that's what we've had to do.
"When we moved the ball properly we looked a decent side but you've got to defend well and you've got to start well.
"We do it one game and not the next, we've got to be consistent in that because you don't give yourself a chance to get a foothold in the game."
This was not the first time Scott had to warn his side about the perils of a slow start - but never before have his side been chastened quite so ruthlessly.
An error-strewn opening went punished as early as the third minute when Aldershot twice failed to clear their lines, the dangerous Scott Neilson jinked his way to the right hand byline and swung over a cross for the unmarked John-Lewis to plant a firm header into the near corner.
Two minutes later the ball was in Aldershot's net again when Alan Goodall's free kick was headed into the net by a stooping Neilson, but referee Wayne Barrett ruled he had impeded Adam Webster. It was a huge let-off.
Still, the Shots had not learned their lesson and Grimsby made them pay by doubling their advantage.
Poor marking was again to blame when Joe Oastler gave away a needless free kick out on the right, Sam Hatton swung the ball in and Hannah stole a yard at the near post to glance a header past Tom Pope.
Thankfully, this time it sparked a response from the Shots with Martin Rowlands and Mark Molesley both going close before they got the benefit of good fortune on 29 minutes.
Chris Barker's corner from the right was half-cleared to Manny Oyeleke 15 yards out and after he went to ground in a tussle with Paddy McLaughlin, referee Barratt pointed to the spot to the surprise of the majority in the ground.
Six-goal Williams won the on-field debate as to who was going to take the kick, but his effort was pushed away by McKeown to his right.
The Irish keeper was at it again two minutes later when the dangerous Oyeleke burst through the middle but his fierce shot was well turned away by an out-stretched arm for a corner.
Captain Craig Stanley then saw a downward header go inches wide just after the restart - but seconds later the Shots were hit by the sucker punch.
Hearn received the ball out in an innocuous position on the right, but after appeals for a foul on Webster were waved away by the referee, the Mariners substitute turned and looped a deft angled chip over the back-tracking Pope and in off the far post.
Molesley sparked the response with a characteristic 20-yard effort which flew just wide, while substitutes Matt Paterson and Jaydon Gibbs both tested the flawless Grimsby keeper in a desperate late foray.
This, however, was simply not Aldershot's day.