Visibly shocked Coe shook his head in disbelief and sighed: "If Diane Modahl is on drugs then there is no hope for athletics."
As it happened, Modahl, 28-year-old Olympian who was the reigning Commonwealth Games 800 metres champion, was eventually exonerated following a ban and a lengthy appeal process. It transpired that there had been serious flaws in the testing procedure and her sample had actually 'mimicked' a positive reading for the performance-enhancing drug testosterone. The popular Mancunian always maintained: "I have never taken any banned substance."
No doubt the now Lord Coe had a sense of déjà vu last week as he declared his candidacy for the Presidency of the International Association of Athletics Federations (IAAF) amid an approaching tsunami of shame which threatens to swamp his sport.
If the Russians really are operating a state-sponsored doping programme in collusion with corrupt coaches and administrator, including one within the IAAF itself purportedly bribed to cover up a positive test, as a German TV documentary alleges, then once again he must be wondering if there is any hope for athletics.
Alas, unlike the Modahl case, this seems unlikely to prove a false alarm.
If charges that 99 per cent of the Russian Olympic team are involved in doping, with the active assistance of the Putin Government, are true, can there really be any viable future for such a disfigured sport?
Coe's initial reticence to comment on the subject has drawn criticism but this does not mean the double Olympic gold medallist is running scared of facing up to the situation realistically; though a subsequent observation from him in Monaco at the historic International Olympic Committee (IOC) session was disappointingly anodyne.
"They are very serious allegations," he said ."The very fact that the allegations are in the public domain means that they are serious. So, we have to be very clear that this is a very, very difficult time for our sport."
Moreover, he appeared to have been beaten to the punch by the man in the opposite corner in the forthcoming scrap to become athletics' main man.
Sergey Bubka, a somewhat late convert to the anti-drugs campaign, could not have been quicker off the mark to score points in the opening round.
"I am deeply shocked and understand that we need to act quickly and transparently now in order to protect the integrity of our sport," stated the Monaco-based Ukrainian, like Coe an IAAF vice-president.
"Very serious allegations have been made in the German (ARD/WDR) documentary involving such a large number of athletes and officials.
"I believe in a zero tolerance policy against doping and we have to consistently and relentlessly fight against what is the biggest threat to sport in the 21st Century.
"We have to educate and guide athletes at a very young age about the dangers and the risks of doping. No athlete thinks about doping when they are at the start of their careers. We should fight the criminal networks, which make millions on doping and we should punish also doctors, judges, coaches, managers and others if they are involved in doping and corruption.
"This is not an easy task due to different laws in different countries. But without fighting the whole network, one cannot win the fight against doping...What we ultimately need to achieve is a total conviction by the athletes and their entourages that clean competition is the only option for the future of sport."
Some observers suggested that this is the sort of fighting talk we should have heard sooner from Coe. But in fairness to Seb, there is nothing Bubka has said that Coe himself has not been saying for years.
For almost as long as I have known him he has been on doping's case, even advocating banning entire nations from competition should their athletes repeatedly transgress.
While the gloves may be off in the big fight with Bubka, Coe, who I believe would be the ideal figurehead for world athletics, insists it is no grudge match.
"Sergey and I go back a long away and will remain friends irrespective of the outcome," he tells us.
However Coe's familiarity with the hustings as a former parliamentarian should have told him that his wily old pal would turn this into political punch-up at the first opportunity, which is perhaps why he should have got his retaliation in first.
Aware that drugs would be such a major issue, it is a pity that Coe's otherwise compelling election manifesto address devotes less than 100 words to the subject of increasing anti-doping resources "in the battle for our sport's integrity."
Coe must re-mount his soap-box soon if he is not be be gazumped by the former world record- breaking pole vault czar who still craftily knows how to raise the bar to his own advantage.
The fact that there is a worldwide conception that top level success in athletics is now determined more by the syringe than the stopwatch is the most crucial matter Coe has to publicly address.
Of course he will know that athletics is by no means alone in having a leading role in sport's dope opera.
There is hardly a major a sporting discipline left that the chemists haven't juiced up, from cycling to weightlifting via tennis and boxing.
You have only to glance at the bulging biceps and tree-trunk thighs of those modern mammoths in both codes of rugby to know that it hasn't all been done by press-ups. And as for America's NFL-well, don't even go there!
Doping may appear to be rampant in Russia - now there's a surprise - as it is suspected in several other countries whose athletes consistently produce eyebrow-raising performances.
But the suggestion that officials can be bribed to allow doped athletes to buck the system becomes the ultimate obscenity.
So no more pussyfooting please. Time to call the cops.
Yet Britain's Sir Craig Reedie, President of the World Anti-Doping Agency (WADA) says he is "completely opposed to the criminalisation of athletes." So, apparently, is the UK anti-doping body, whose interim chief executive Nicole Sapstead declares there is "no appetite" here to illegalise doping, adding: "I don't think there is a need for dawn raids and smashing down doors."
Why not, if this is what it takes to clean up sport and make a sceptical world believe in it again.
Otherwise the cheats will always be one pace ahead of the game
The Germans propose three-year jail terms for those caught using and supplying performance-enhancing drugs. Other nations must follow, and it would be heartening to hear such strictures loudly endorsed by Lord Coe - preferably before the bandwagoning Bubka does!
Alan Hubbard is an award-winning sports columnist for The Independent on Sunday and a former sports editor of The Observer. He has covered a total of 16 Summer and Winter Games, 10 Commonwealth Games, several football World Cups and world title fights from Atlanta to Zaire.