He was right to be concerned. The Dutch media observed 24 hours later that the match against Scotland reflected the worrying state of the national team, a 1-0 victory achieved ostensibly only because of the inadequacies of the home side, who pooped their own party as Hampden Park was reopened.
To envious Englishmen watching the Dutch take the high road to the World Cup finals, though, they looked remarkably well given that Ruud Gullit, Marco van Basten, Ronald Koeman and Jan Wouters were absent. The margin could have been trebled as the Dutch extended an unbeaten record to 11 matches - though that can be deceptive, as Bobby Robson and Graham Taylor found out. It was a bit like sightseeing: locals always complain at how bad things are compared to the old days; visitors are often surprised at how much beauty is left.
Fretting and pessimism have been a way of life for Dutch football ever since that World Cup final of 1974 when Johan Cruyff and a few of his nervous team-mates missed Rinus Michels's pre-match talk. They were puffing on cigarettes in a corridor of Munich's Olympic Stadium as a prelude to establishing themselves as the best team never to win the tournament.
Indeed, they surprised themselves by beating England in Rotterdam last November, it seems, and the Uncle Mort atmosphere has barely changed since. 'It depends on the results,' Frank Rijkaard, a Marlboro man himself and reluctant captain last week, said of the feeling in the country for the team. 'We didn't play a terrific series in qualifying and against England we were a little lucky.' Advocaat added: 'Holland is like England. The people want only winning teams.'
The Dutch have often been their own worst enemies. Four years ago the atmosphere within the camp was so sour, with players hostile to the then coach Leo Beenhakker, that the outstanding potential of great players at their peak went to waste.
'We played very bad. There was no real unity in the team,' Rijkaard said, his face screwing up as he was forced to recall those days. And this time? 'It is too premature,' he said, aware of the potential pitfalls, even if all seemed warm and relaxed in front of the fire in the lobby at the Loch Lomond hotel.
Another survivor of Italia 90, Hans Gillhaus, believes the coals should glow brighter this time. 'We became a team too late last time,' he said. 'We have all matured for four years now, that's the biggest difference. And everybody knows that this is the last chance for this generation.'
The welding together of intelligent, opinionated players - notably the nucleus of thirtysomethings - will be Advocaat's main task, one senses. 'That is the skill of the coach,' he agreed with a smile. The real benefit of a wet week near Glasgow, which bears little relation to a summer month in Florida, may be the basis of harmony established within the camp at the beginning of the last leg of the World Cup campaign.
Advocaat is an approachable, unassuming man and his more manageable ego, amid the more developed versions which many of those around him possess, should help the team to be more productive. It may prove just as well that Dutch football's governing body was unable to reach agreement with the more commercially minded Cruyff for him to take over the team for the World Cup finals. Without wishing to give Terry Venables ideas, one of Cruyff's demands was that the team wear his own brand of sportswear.
Advocaat has compromised over Gullit, who himself has abandoned his self-imposed exile from internationals and has agreed to play wide on the right, after talks with the coach. 'Things are good between us,' Advocaat said. 'He will be one of the 22.' He will surely be more than that. With Van Basten unlikely to be fit, Gullit may even serve as the central striker with Dennis Bergkamp playing off him, according to insiders.
Advocaat will not commit himself on the subject, but says he has already decided. He also knows what his squad is likely to be, although he may be pondering some back-up, such as the bold inclusion of Pierre van Hooijdonk, the 17- goal, 6ft 4in Breda striker - the Dutch have always liked the option of an extra target man or two - the Ajax midfielder Edgar Davids and Stan Valckx, the Sporting Lisbon full-back.
Whoever the Dutch employ - and Danny Blind looked a solid replacement for Ronald Koeman at the centre of defence while, despite his indifferent season with Internazionale, Wim Jonk appeared a quicker, more cultured alternative to Wouters in midfield - they have their fluid 3-3-4 formation and their formidable technique to rely on.
Were one to have intermittently frozen the action against Scotland, who began their latest attempt to catch up with Europe by playing a sweeper and with full- backs pushing forward, one might have seen six Dutchmen in attack then, in the next frame, eight in defence. Never was a Dutch player in possession without support within 10 yards; so often a Scot was isolated.
Before the match in Glasgow, a group of Scottish schoolboys went through a demonstration of skills devised by the innovative Dutch coach Wiel Coerver. Watching the methods employed emphasised that a volley by Van Basten or an acutely angled turn by Bergkamp are not just the products of natural ability - they are skills honed by lots of hard work.
It was no coincidence that every Dutch player in the subsequent international looked balanced, the ball seeming to belong at his feet, while it frequently seemed to bobble a yard away from some of the supposed better talents in Britain.
One suspects that when Venables talks about wanting mobile, flexible footballers for England, he has Dutch role-models in mind, their attributes allied to the heart and determination of the Germans. He did, after all, once try to sign the Netherlands' goalscorer against Scotland, Bryan Roy, for Tottenham before he was lured by the lira to play for Foggia in Serie A.
Technique alone does not, of course, win matches. 'Sometimes we wish we had the mentality of the English and Scottish players,' Advocaat said, and he has worked hard at instilling the ethos of hard work into his charges. Technique does go a long way, however, and it cannot quickly be acquired.
History shows, too, that World Cup-winning teams often feature a core of talented, experienced players fronted by a young goalscorer seizing his chance: Pele in 1958 or Geoff Hurst in 1966, for example.
The theory applies to the Dutch. 'They are one of three European countries who could win the World Cup, along with Italy and Germany,' the Scotland coach, Craig Brown, said. 'They have the flair. Germany are very solid and Italy have one or two flair players as well, but Holland have great quality throughout.'
In practice, questions remain, given a lack of pace through the centre of the team due to ageing and doubts over Bergkamp's ability to fulfil the role of the hungry kid after a difficult first season in a patchy Internazionale side who have too readily thrust responsibility on him.
Matches against the Republic of Ireland in Tilburg on 21 April, Scotland in Utrecht on 27 May, Hungary in Eindhoven on 3 June and Canada in Toronto on 10 June before their opening World Cup game against Saudi Arabia in Washington DC on 20 June could provide us with the answers.
But we may learn more by gauging the atmosphere in their camp as the Dutch take on their toughest opponents - themselves.