There was supposed to be nothing but celebration on Tuesday night. Scotland put four past Curacao in a send-off fixture designed to build momentum and confidence ahead of the nation's first World Cup since France 1998 — a 27-year absence that has weighed heavily on every generation of supporter in between. Instead, the night ended in an anxious silence when Billy Gilmour went to ground clutching his right knee in the 42nd minute and did not return.

The Napoli midfielder had been involved in a physical collision earlier in the half, and while he played on briefly, his body eventually refused the deal. Clarke withdrew him at the interval, and the manager was frank in the aftermath, telling reporters he was "praying" for good news when Gilmour's scan results come back. That word — praying — is not the language of a man who expects clean news.

For those who have watched Clarke build this Scotland side over several years, the centrality of Gilmour to the project is not a matter of debate. He is the player who sets the tempo, who wins the ball low and moves it quickly, who gives the side its technical backbone in a team that is otherwise built on industry and organisation. Scotland have other options in the engine room, but none who offer what Gilmour offers: the ability to play out from pressure, to control a game rather than simply compete in one.

Scotland are scheduled to fly to the United States within 24 hours of the scan results being assessed, which compresses everything. Clarke has effectively no margin. The World Cup draw has placed Scotland in a group that will demand every functional piece of the squad from the opening whistle — this is not a tournament where a side of Scotland's ranking can absorb an injury to their most technically gifted outfield player and adjust gradually. The stakes of the scan are immediate and absolute.

The injury also arrives at a moment when Gilmour had been in genuinely sharp club form for Napoli, suggesting this is not a player carrying fitness concerns into the tournament but one struck by the misfortune of contact during a game that was, by the 42nd minute, already heading comfortably in Scotland's direction. The 4-1 scoreline flatters the occasion's low stakes, but the injury does not care about the scoreline.

Clarke, to his credit, did not dress the situation up. He confirmed Gilmour would undergo a scan, said he hoped the news would be positive, and acknowledged plainly that the timing was as bad as timing gets. There is nothing to be gained from false reassurance at this stage, and Clarke has never been a manager who reaches for it. The squad and support will know the full picture when the medical staff have one.

What hangs over all of this is the weight of the occasion itself. Scotland's 1998 World Cup campaign ended in group-stage elimination, with a defeat to Morocco the final note. The intervening decades have carried enough near-misses and qualifying collapses to make this qualification feel genuinely hard-won — not a lucky passage but the result of Clarke's methodical reconstruction of a squad culture that had become accustomed to failure. To have that effort potentially diminished by a knee injury in a warm-up match against Curacao is the kind of thing that tests even the most disciplined footballing stoicism.

The scan results will define the mood of Scotland's entire preparation. If Gilmour is cleared, the 4-1 win becomes the story it was meant to be — a confident send-off, a nation heading to America with belief. If the news is bad, Clarke faces real decisions about whether a replacement can be called into the squad and whether the tactical plan needs to shift before a single competitive minute has been played. Either way, Scotland now arrives at the tournament's doorstep not with the clean certainty they wanted, but with one eye on a medical report and one hand on every available piece of wood to knock on.