So much remains still on the line in this Nations League campaign. So much will be resolved in the Cracovia stadium on Tuesday night in another high stakes encounter with Ukraine. It could – whisper it – be another red-letter day in the Scottish football team’s recent history. There’a also the bleak possibility of (yet) another so-near and yet-so-far scenario.

Defender Jack Hendry’s header five minutes into the second half after fine play on the left from Ryan Christie revived Scotland following the double blow of losing the first goal and left-back Kieran Tierney with a head knock.

Scotland pushed for a winner. They secured it in nerveless style when the superb Christie sent Gavin Bazunu the wrong way from the spot with nine minutes left after substitute Allan Browne handled John McGinn’s corner.

Ryan Christie confidently converts his penalty to give Scotland a 2-1 lead over Republic of Ireland.

It hasn’t altered the situation greatly and nor does it significantly ease Scotland’s task against Poland. Steve Clarke’s battered and bruised side – Scott McTominay is also suspended after collecting a needless booking in a late melee – still need to avoid defeat in the ancient Polish capital to secure top spot in Group B1.

Avoiding defeat here in Glasgow was the chief target. Scotland had Craig Gordon as well as Hendry and Christie to thank for ensuring there was no slip-up. The 39-year-old goalkeeper’s partner Summer gave birth to a son yesterday and his participation had been placed in some doubt.

But he keeps on underlining his importance to Scotland and, indeed, his commitment to the cause, no more so than when he blocked Troy Parrott’s shot after 55 minutes after lightning quick break by the visitors left the keeper facing a two-on-one situation. Happily for Scotland and Clarke, Gordon continues to defy the odds.

The pre-match atmosphere resembled some memorable nights of old. It also called to mind another Saturday evening match from more recent history – against Italy in 2007. Admittedly the drunkenness was not at the level of that wild occasion. Neither was it quite as do-or-die.

Scotland were awarded the penalty after Irish substitute Alan Browne handled the ball.

But the old stadium has rarely plunged so quickly into silence as it did after 38 minutes as Tierney fell clutching his head after a collision with Parrott in the box. In the words of the dear departed Arthur Montford, it felt like a disaster for Scotland – with no disrespect intended towards Greg Taylor, Tierney’s replacement. It just illustrates the vital role Tierney plays and the esteem in which he is held by the Tartan Army. The fact Scotland were already trailing didn’t help the sudden fatalistic mood, which was in marked contrast to the bedlam at kick-off.

Tierney, who is still returning to full fitness after injury, was one of those Clarke revealed he was swithering over on the eve of the match. If only, if only. If only Swiss referee Sandro Scharer had produced a second yellow when Josh Cullen tripped Aaron Hickey moments after the Irish player had been booked for kicking the ball away. A thrilling second half comeback from Scotland saw such regrets melt away – for the time being at least.

There was some evidence of nerves as Scotland tried – and failed – to start up where they left off against Ukraine in midweek. Clarke had decided against too many changes, in the end opting for only one other than Hickey’s continued deployment at right back – Lyndon Dykes replaced Che Adams up front.

With the visitors effectively playing with two high forwards in Michael Obafemi and Parrott, it might have been a night for reverting to three at the back – although that clearly hadn’t worked in Dublin. Whatever the whys and wherefores, Scotland struggled to take grip of the midfield in the initial stages. McGinn’s 50th cap wasn’t quite working out as planned. A Stuart Armstrong cross from the right offered the skipper a chance to mark the occasion with a goal but he messed up the connection.

Jack Hendry glances home Scotland's equaliser at Hampden.

A Parrott goal for the visitors after 11 minutes which was ruled out for offside could hardly be described as a let-off – he was at least a couple of yards offside when he sprinted onto a through ball from Darren O’Shea before thrashing a shot into the roof of the net. But it was a sign of Republic of Ireland’s determination to gain an early foothold in the game, just as they had done in June. And just as was the case earlier in the summer, they opened the scoring from a set-piece. Michael Obafami, who did so much damage in the Avivia stadium, picked McTominay’s pocket in midfield and a Parrott shot was blocked by Hendry at the expense of a corner.

James McClean shrugged off the boos of the Hampden crowd and slung in a cross that was met in the area by Dykes, back doing his bit in defence – another reason, other than his two goals in midweek, to explain his preference over Adams.

However, any sense of the danger having passed was short-lived. Jayson Molumby was first to the ball, knocking it back into the danger zone. Defender John Egan turned to whip a ferocious shot past Gordon.

If this wasn’t deflating enough, then came the Tierney blow. Taylor was eventually summoned as the Arsenal full back departed groggily down the tunnel. It felt like a potentially defining moment. But this Scotland side has proved itself capable of withstanding the loss of such a crucial player.

Greg Taylor, Tierney’s replacement, even had a hand in the equaliser, linking up well with Christie on the left.

The latter player left Matt Doherty in the kind of Hampden daze he might remember from the 2012 Scottish Cup final, when he played for Hibs against Hearts. Christie then lifted the ball into the danger area. The unmarked Hendry saw his header hit the post before nestling in the net.

Christie’s penalty winner means Scotland head to Krakow in a winning frame of mind – and with the cheers of a joyous Hampden crowd still ringing in their ears.

The comeback, that save, the momentum - thrilling Scotland win against Ireland sets up red-letter day in Krakow