Glasgow: Super sub John Guidetti grabbed a stoppage-time equaliser as Celtic twice came from behind to secure a 3-3 draw in a thrilling Europa League round of 32, first-leg tie in Glasgow on Thursday.
Xherdan Shaqiri opened the scoring in the fourth minute after a mistake from `keeper Craig Gordon before Rodrigo Palacio drilled home a second in the 13th minute.
Two Celtic goals in a minute then turned the game on its head, as Stuart Armstrong lashed home on his European debut for the club before Hugo Campagnaro fired past his own `keeper.
The home side looked the more likely to add to their haul before another howler from Gordon allowed Palacio to make it 3-2 in the 45th minute.
The second half was tame in comparison but, with the match deep in stoppage time, Swedish striker Guidetti lashed home an equaliser to leave the tie in the balance before the return in Milan next week.
"It was an unbelievable football match played in an unbelievable atmosphere," Celtic manager Ronny Deila said.
"I`m so proud of the boys to come back from 2-0 down, especially against an Italian team. We caused them problems and got a result in the end."
Inter manager Roberto Mancini said: "We played a good game and started very well. We scored two goals and after this we thought it was an easy game.
"We were never finished and we took our chance to come back into the match but Celtic are a good team."
The hotly-anticipated game was a rematch of the 1967 European Cup final in Lisbon, when Celtic triumphed 2-1 to become the first British club to be crowned champions of Europe.
Memories of the greatest moment in Celtic`s history were evoked before the match with many of the surviving members of Celtic`s Lisbon Lions forming a guard of honour for the current crop as they took the field.
A wall of noise from the first 60,000 sell-out crowd of the season at Celtic Park pushed the home side forward in the opening minutes but they were stunned into silence when Inter took a fourth-minute lead.
Gordon had gone 816 minutes without conceding a goal before the 2-1 win over St Johnstone on Saturday but the `keeper made the poor decision to save Shaqiri`s first-time shot despite it appearing to be going wide.
The Swiss international made no mistake with the rebound as he squeezed the ball under Gordon and into the far corner from close range.
Another defensive error allowed the Italians to grab a second in the 13th minute. Emilio Izaguirre`s attempted clearance from Shaqiri`s ball into the box came back off Virgil van Dijk and into the path of Palacio, who rifled the ball through the legs of Gordon.
Inter appeared to be on course for a comfortable victory but the good work of their explosive start quickly came undone as Celtic grabbed two goals in a minute to level the tie.
The first came in the 24th minute when Adam Matthews collected a Stefan Johansen pass before cutting the ball back from the by-line for Armstrong to drill the ball behind Juan Pablo Carrizo.
The Italians had barely time to regroup before Johansen hooked a long throw-in into the box where Campagnaro, under pressure from Armstrong, bundled the ball beyond his own `keeper.
Disaster struck for the hosts on the stroke of half-time following another howler from Gordon, however.
Gary Medel`s long diagonal ball should have been easily claimed by the Scotland international but he dropped the ball at the feet of Palacio who had the simple task of tucking home his second of the match.
A mistake by the Inter defence allowed Gary Mackay-Steven to nip in behind them but his tame effort was saved by the outstretched leg of Carrizo.
The Hoops were then screaming for a penalty in the 66th minute when Johansen appeared to be bundled over in the box but Hungarian referee Istvan Vad ignored their pleas.
Time appeared to be running out for Celtic before Guidetti, on for Leigh Griffiths, latched on to fellow sub Liam Henderson`s pass to fire a fine finish past Carrizo.