"I remember a little bit of the second."
The incident happened in the game's opening minute and it had a back story. Lonergan was no fan of Australian prop Steve "Blocker" Roach. In short, he thought the Balmain hard man was all mouth and no trousers.
When Balmain visited Carlaw Park to play Auckland in a pre-season game earlier in 1991, Lonergan had been in a punch-up with Roach.
"I got him. His nose exploded," Lonergan recalls.
"All he did in response was to spit all this blood on my face."
Lonergan, a born-and-bred Westie, was keen to re-acquaint himself with Roach when the two teams met at Melbourne. In the game's opening minute he saw an opportunity for a big tackle, lined Roach up, got his head in a horrible position and the results were messy.
Lonergan was off for a mere 10 minutes, which sounds obscene now but was probably unremarkable back then. Lonergan concedes his memories of the night are vague, but he reckons the sight of George Mann going on to replace him would have acted as a spur.
Mann was in great form; many people believed he should have been starting the test anyway, and Lonergan reckons he would have been extremely reluctant to let him have a free shot at his position without the chance to respond.
"As my head cleared I believe I told [coach] Bob Bailey that I was going back on," Lonergan says. "I don't think I was any good but I was determined to be out there."
Back in New Zealand, a different sort of drama was playing out. Rob Allen, the brother of All Black Nicky Allen, who died after a catastrophic head injury suffered in a club rugby game, was watching and he didn't like what he was seeing.
"I recognised immediately he was behaving in a similar way to Nick. I had seen the video of Nick and he was fitting in a way that was very similar to Dean," Allen recalls.
"Then he came back on and I couldn't believe it. I was thinking if he gets a tap on the head he was literally going to die."
Allen worked the phone, trying to work out how he could get a message direct to the stadium to get Lonergan off the field and keep him off. He couldn't get through.
"I was beside myself," he says. "Ask any medical professional what it means when you're fitting. There's not a neurosurgeon in the world that would say it was okay for him to return to the field."
About the only concession Lonergan made to his misfortune was that he didn't follow the rest of the Kiwis out on the tiles that night.
"I went back to the hotel and went to bed. The Mad Butcher, being the good bugger he is, stayed with me and talked to me all night."
It was far from the only time Lonergan was concussed during his league career that spanned Glenora Bears, City Newtown, Auckland, Canberra Raiders, the Kiwis and Rochdale Hornets.
"I got hit in the head a few times, and the first thing that happened was I always got this weird feeling of deja vu, this detached feeling of 'geez, I've been here before'.
"Then you shake it off and carry on."
Curiously, several former players the Herald has talked to have spoken about the feeling you get with concussion and talked about the deja vu effect, and some have even said it's not an unpleasant feeling.
"Has it had a long-term effect? I can't tell you that because I only have myself to compare to. I had an MRI scan a few weeks after the big hit in Melbourne and it came back all clear.
"I didn't suffer headaches or anything like that. But who knows, maybe when I die they'll cut my brain open and say 'shit he's messed up'."
Tell us your story: If you have had problems with concussions received playing sport contact us at target='_blank'>sportrac@nzherald.co.nz.
Rugby and brain injuries
On day one of the Herald's special report, we examined the growing evidence which links multiple head knocks and long-term neurological disorders, and the potential impact this has on our rugby codes.
Yesterday
We spoke to Rob Allen, brother of dead All Black Nicky, who believes the NZRU have been covering up the risks.
Tomorrow
We conclude by looking at what the future holds for the national game and talk to Mike Sabin, whose son Darryl suffered a catastrophic brain injury on the rugby field.