Celtic face a journey to Inter Milan's great cathedral, the San Siro, having taken a step back from the edge of a cliff.

There are flaws in Ronny Deila's side which will surely still cost them a place in the last 16 of the Europa League, but let no-one question the vim or guts they bring to these big nights.

They looked dead and buried twice in this wonderful spectacle, 2-0 down early on and 3-2 behind with only seconds left, but they the fought and drove and battered their way through Inter Milan. There was skill and intelligence in some of their play. Above all it was about character and resilience, though.

Stuart Armstrong and an own goal steadied Celtic after they conceded twice in 13 minutes before, unthinkably, a headline blunder by Craig Gordon, the goalkeeper without whom they would not have survived so far in the tournament to be playing Inter at all. He misjudged a long ball and stretched and clawed it like a children trying to reach bubbles in the air, and it got away from him for Rodrigo Palacio to score his second of an intoxicating night.

For almost half of the game the looked like the winning goal until John Guidetti suddenly reintroduced himself to Celtic, lurching the spotlight back onto himself with a superb equaliser at the death after months of drab form.

Still, excitement must be tempered. This is an admirable outcome against a team of Inter's resources but it's no-one's idea of the sort of home result to take to Italy.

Celtic again displayed the flaw which has disfigured their Europa League campaign all season. After 13 games they have conceded 22 goals, too many for them to make a convincing case for keeping the clean sheet they would surely need to survive the second leg.

This was a rainy February night in Glasgow infused with the spirit of a sweaty May day in Lisbon. 1967 had saturated the build up and Parkhead was further roused by footage of the Lisbon Lions on screen then a walk-on part for the men themselves, taking to the field before kick-off along with two of the Inter players they beat. Not that Parkhead needed much rousing. Oh, the place simply crackled.

Inter's attempt to puncture and deflate the excitement was successfully completed within the first 13 murderous minutes, by the end of which they had scored twice. Jason Denayer put Adam Matthews under pressure with a difficult pass and when Zdravko Kuzmanovic robbed him he quickly chipped a ball over the top for Xherdan Shaqiri. The exquisite Swiss playmaker scored at the second attempt after Gordon saved his first attempt when it should have been left to hit the side netting.

Celtic's opening was sluggish and conceding so early rattled them. When Inter won a corner the delivery reached Shaqiri and his ball back into the box wasn't dealt with by Emilio Izaguirre or Virgil van Dijk, allowing the Argentine Palacio to take it and apply another crisp finish through Gordon's legs.

Celtic were being overrun in midfield, with Scott Brown and Nir Bitton chasing Inter's diamond-shaped four. Their passing was nervous and careless. Inter were snuffing them out all over the park until suddenly Stefan Johansen drove a ball to Matthews who did well to force himself free from a defender and attack the line. His cross picked out Armstrong to bury a sweet finish an embellish his tremendous European debut.

Armstrong was initially credited with the equaliser for 2-2, as well, but his telling contribution did not quite stretch to that. Matthews' throw-in was looped into the goalmouth by Johansen, briefly disorientating the Inter defence and allowing Armstrong to steal in and force the ball off Hugo Campagnaro for an own goal.

Suddenly a natural high was coursing through the Celtic players' veins. The 50-50 balls were now theirs, the passing was sharper, the attacks propelled by soaring self-belief. What an almighty effort Johansen, Mackay-Steven, Armstrong and Leigh Griffiths applied, running constantly to harass Inter.

Celtic had their best 20 minutes of the night, playing brightly, and then came Gordon's grotesque misjudgment. Gary Medel's long, hopeful through ball was the goalkeeper's all night long but he came for it and came for it and came for it and the ball travelled and travelled and travelled until the whole stadium could see it would elude his desperate, flailing fingers.

Palacio was waiting at the end of its trajectory, like a vulture, and tucked away the easiest goal of the night. Gordon hated himself, as a chant of "one Craig Gordon" sprang up in the stands. His sure handling of some Inter half-chances in the second half, and one fine save from Shaqiri, steadied his nerves but did nothing for his mood.

Bitton fizzed a shot wide and there were howls for a penalty when Johansen went down as he almost put Griffiths in. Celtic gave everything they had and they worked Inter hard, but it just didn't look as if they could save themselves.

Inter finally looked like they had a win in Glasgow after three previous failed attempts stretching back almost 40 years. And then, in stoppage time, Guidetti took Johansen's pass on his chest and rifled it into the roof of the net for a terrific striker's finish. There was one final act of sweet drama: Shaqiri's free-kick was going in until Gordon's great save, generating the last and warmest roar of a mesmerising night.