It's win or bust for Scotland against Croatia on Tuesday, and they now know that victory guarantee them a place in the knockouts for the first-ever time. Given that Euro 2020 is Scotland's first major tournament in 23 years and they're 30 places below Croatia (14th) in the FIFA World Ranking, this might seem -- on recent international form alone -- a herculean task... especially now star midfielder Billy Gilmour is out of the match after testing positive for COVID-19.

But if you listened to what the players were saying after Friday's battling 0-0 draw vs. England at Wembley, you understand the class of '21 aren't there to party. They want to do something special.

As Scotland head coach Steve Clarke carried out his final postmatch media duties on the Wembley pitch, you could hear the song "No Scotland, No Party!" coming from the hospitality boxes. It was like birdsong as it cascaded around Wembley, with a pocket of Scotland supporters still soaking up their well-deserved point against the "Auld Enemy."

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Clarke was his usual realistic self, despite having just outplayed England in a game that neatly tees up Tuesday's final group game. The goalposts were still being dismantled behind him, but Clarke was already turning his attention to Tuesday. The former West Bromwich Albion manager has ensured Scotland's product is greater than the sum of its parts, and harnessing the collective work ethic and chemistry that frustrated England will be essential when Croatia roll into Glasgow.

Still, Scotland never do things the easy way, and will have to be without the outstanding Gilmour -- Star of the Match against England -- due to his positive test on Monday. His absence will be a real test of the Scotland collective spirit.

Scotland have never before qualified from the group stage of a World Cup or European Championship in 10 previous attempts. And this group of players can make history.

Prior to their Group D opener against Czech Republic, there was a thin line between joyous nostalgia and present-day pessimism around Hampden Park. The newspapers were harking back to 1978, when Scotland went to the World Cup with every intention of bringing it home. They even had an open bus tour before the squad departed for Argentina, only for them to come back far too quickly, having lost 3-1 to Peru and drawn 1-1 with Iran.

The 2021 squad has distanced themselves from any expectation. They've been based at Rockcliffe Hall in Darlington, northern England -- about 45 minutes south of Newcastle -- for the tournament as Czech Republic had already snapped up their usual base in Edinburgh. The Scotland bus was held up on the M8 as it journeyed into Glasgow the night before their game, with cars honking their horns and weaving through traffic to get a glimpse of their heroes through the tinted windows. On game day, they were hit by Patrik Schick's double-decker of goals and lost 2-0.

The second, a stunning long-range effort that was the longest goal ever scored at a men's tournament final, popped the Scots' balloon and dissolved the atmosphere inside Hampden Park, but Clarke remained resolute afterwards. "We didn't come here for a learning experience; we came here to be competitive."

England's opening 1-0 win over Croatia meant that Friday night's meeting became even more important to Scotland, who needed a positive result to keep qualification hopes in their own hands. Kieran Tierney was fit, and the Arsenal defender ended up being one of four changes: he started at centre-half with Che Adams, Callum McGregor and Billy Gilmour also getting the nod. All four were magnificent as they reduced England to just one shot on goal, while creating chances to win it.

As the 2,500 or so Scotland fans inside Wembley soaked it all up, there was one almighty party going on in Leicester Square. An estimated 40,000 Scotland supporters travelled south to be in London for the match; it was a tartan migration. Wherever you went in central London on matchday, even down on the Underground, you'd hear "Super" John McGinn's name being sung, or "Yessir, I can boogie!" (Scotland's adopted anthem for the Euros). After the match, it was Gilmour's name cascading round Wembley.

Gilmour, 20, has only started five Premier League matches for Chelsea, but he's clearly learning from teammate N'Golo Kante. While it was only his third cap for Scotland and his first start; he was the calmest presence on the field. The football hype machine went into overdrive over Gilmour's performance -- Graeme Souness, the 54-cap Scotland international, said on television that "little boy Gilmour was fantastic" -- but within the camp, it was "no surprise," according to manager Clarke.

Defender Andy Robertson spoke with Gilmour on Friday afternoon, checking how his nerves were, only to find that "nothing fazes him." The young midfielder texted his parents on the way to the game, telling them he was starting. They were there in the stands, with his No. 23 on the back of their shirts.

"It was his big moment and he didn't let us down," Clarke said. But now they'll be without him for Tuesday's match. It's a hammer blow for Scotland and their midfield balance.

With Gilmour absent, Clarke may opt to move Scott McTominay into midfield, or draft in Southampton's Stuart Armstrong. Either way, they need to move on from the setback and find a way to land their own punch on Croatia up front. While Scotland's defence has looked largely sturdy in their two matches, scoring goals at the other end remain a problem. Clarke went with just Lyndon Dykes up front against Czech Republic, with Ryan Christie playing in behind, but he started two recognised strikers against England -- playing a 5-3-2 in defence, 3-5-2 in attack -- with Adams partnering Dykes.

Scotland's sole shot on target against England was from right-back O'Donnell, while centre-back Jack Hendry came closest against Czech Republic when he hit the bar with a speculative effort from distance. Former Scotland international Don Hutchison told ESPN that "the next step against Croatia is getting Adams more chances -- more runners from midfield might be key." He expects to see an unchanged team, but would like to see McGinn giving more attacking license.

Tuesday's pivotal game will come down to whichever team can take their chances; Croatia have also struggled to create, making it anyone's game. As ex-Scotland midfielder James McFadden said, "we're creating chances, we're just not taking them. We need that composure in front of goal."

Clarke said after the England game that his players "deserved a bit more respect," labeling the Croatia match a "cup final." His captain, Liverpool defender Robertson, was already focusing on the third match.

"The feeling that we have now, the feeling that the fans have, it's important we keep that and it's not for nothing," Robertson said. "We take it down to the last game and that's all we ask. We have to use it to get out of the group."

Before the tournament, Robertson gave each player a gift box filled with home comforts: There was Irn-Bru (a bright orange soda), some Scottish shortbread, a bottle of whiskey and some cans of beer. Now Scotland need to determine whether they'll be using that to drown their sorrows come Tuesday evening, or toasting the knockout stages as the party rolls on.