The relief among the Crusaders was almost palpable after Weepu, a second-half replacement, had his drop goal attempt charged down for the Blues right on fulltime.
It meant the Crusaders started the season with a win after losing last season's final against the Reds and Blackadder will be heading back to quake-hit Christchurch a satisfied man.
The Blues, on the other hand, were bitterly disappointed.
"The video clearly shows a lot of guys offside," Lam said of the Weepu drop goal charge down. "And that was the penalty that we gave away to offside, and that was fair enough, to take them to 19-18, so a nice penalty at the end would have been nice; to knock it over and finish the game, but hey that's the call and we'll just review it and go through the process."
Lam made reference to last season's opener being deja vu, and Blackadder also chimed in on that theme.
"Well, it was never in doubt," were his first, tongue in cheek, words.
"It felt a bit like groundhog day. The stress levels were certainly high in the coaches' box."
The Blues' thrusting backs Rene Ranger at centre and newcomer, wing David Raikuna, were always a handful for the Crusaders, and that, plus the solidity of the scrum will have pleased Lam at least.
But on the other side we caught a glimpse of young Tyler Bleyendaal, Dan Carter's stand-in at first-five, who probably shaded his battle against Michael Hobbs.
His jinking run near the end of the match should have resulted in points but instead the Crusaders coughed up another of their many penalties. This is an issue they will have to fix.
For Weepu, on at first five, after 58 minutes, with Hobbs moving to second-five, it wasn't quite the star turn he could have been expecting after his World Cup heroics.
He was sent flying by a Robbie Fruean fend and landed on his considerable bottom.
The second half was a curious affair with only three penalties scored - two from the Blues and one to the Crusaders.
The Blues settled quicker than the Crusaders in the first half and scored two tries within the opening 10 minutes.
Chris Lowery and Jerome Kaino charged down Israel Dagg's attempted clearance - with Lowery the benefactor - and wing David Raikuna scored his first Super Rugby try, taking advantage of poor Crusaders defence and a big overlap.
Blackadder later revealed that Dagg, who hesitated before trying to clear, was playing on the wing precisely because his niggling quad injury was not yet 100 per cent. But he claimed the Weepu charge down as he felt he owned his teammates something.
In the meantime, though, Bleyendaal had been chipping away. He had closed the gap to 7-3 and then 12-6 with two easy looseners before a piece of Fruean magic allowed the Crusaders to take the lead.
The big centre had the Blues defence backpeddling and his dummy too easily fooled the home side.
With a four-point buffer, the Crusaders were cruising. Their forwards were finding a nice rhythm after some early shocks from the big-hitting Kaino and the dangerous Blues backs saw little ball.
The last four minutes of the half would have jolted the visitors back to reality, however, with the always dangerous Ranger scooting off on a 60m run before he was stopped by a combination of Kieran Read and Sean Maitland, and Alby Mathewson knocking on after going close from an attacking scrum.
The Blues also had a chance to close the gap with a penalty goal as the seconds ticked down but they decided to go for touch and the chance was lost. They may rue that decision given the late dramatics and Weepu's miss.
Bleyandaal was well short with two of his penalty attempts in the second half - he put the lack of power down to a quad injury - but was a calm figure in the No10 jersey. Fruean was a handful and halfback Andy Ellis got busier as the game wore on.
Kaino was immense in defence for the Blues, with props Charlie Faumuina and Tom McCartney playing well.
Read and loosehead prop Wyatt Crockett caught the eye among the Crusaders forwards.
CRUSADERS 19 (Robert Fruean try Tyler Bleyendaal con 4 pens) bt BLUES 18 (Chris Lowrey, David Raikuna tries Michael Hobbs con 2 pens) at Eden Park. Referee: Chris Pollock.
